* Cut target.h into platform specific pieces.

* C_ASSERT is not used there.

* delete unused "REGNUM_MASK'.

* delete redefines of "REGMASK_BITS".

* add headers to JIT_HEADERS

* Resolve ILLink warning on Microsoft.Extensions.Options.DataAnnotations

* Fix build and add annotations to TOptions to try to keep as much as we can

* Stop reading TargetFramework prop in props files

The TargetFramework property isn't expected to be set in props files
before a project's body is evaluated.

Don't let BuildTargetFramework property fallback to TargetFramework as
BTF's sole intent is to convey the TargetFramework to filter to and not
the current selected TargetFramework. Reduce usage of BTF so that it is
only used in places where code is actually conditioned on filtering.

In addition to that, specify BuildTargetFramework as a global property for
all traversal builds so when invoking one of the traversal projects directly
(src.proj, ref.proj, etc.), BuildTargetFramework doesn't need to specified
manually to get the default behavior (filter on compatible to net6.0).
Remove the inferred BuildingNetCoreAppVertical because of that and
inline its meaning.

Make sendtohelix a normal NoTargets proj so that it has access to the
properties which were moved into the Directory.Build.targets file as
otherwise it wouldn't import that file.

* Add S390x value to System.Runtime.InteropServices.Architecture enum

* Add native s390x architecture detection

In addition to making ChaCha/Poly work, this change refactors the "HasTag" implementation.

The CIPHER_HAS_TAG was used to determine if the GCMParameterSpec
configuration is needed for variable length tags.

While ChaCha20Poly1305 has authentication tags, it does not permit a tag
length other than 16 bytes, so there is nothing to configure.

This renames the CIPHER_HAS_TAG to be more specific that the cipher
supports more than one tag length, and removes it from ChaCha20Poly1305.

This simplifies the IV initialization a bit.

[MacCatalyst][libraries] Add specific SkipOnPlatform and ActiveIssues instead of test level skip (#52859)

* [MacCatalyst][libraries] Add System.Console.Tests SkipOnPlatform

* [MacCatalyst][libraries] Add System.Diagnostics.Process.Tests SkipOnPlatform

* [MacCatalyst][libraries] Add Microsoft.Extensions.Hosting.Unit.Tests SkipOnPlatform

* [MacCatalyst][libraries] Add System.Net.NetworkInformation.FunctionalTests SkipOnPlatform

* [MacCatalyst][libraries] Add System.IO.FileSystems.Tests SkipOnPlatform

* [MacCatalyst][libraries] Add Microsoft.VisualBasic.Core.Tests ActiveIssue

* [MacCatalyst][libraries] Add System.Diagnostics.Process.Tests ActiveIssue

* [MacCatalyst][libraries] Add System.Threading.Thread.Tests ActiveIssue

* [MacCatalyst][libraries] Add System.IO.FileSystem.Tests ActiveIssue

* [MacCatalyst][libraries] Add System.Runtime.Extensions.Tests ActiveIssue

* [MacCatalyst][libraries] Remove test project level skips

* [MacCatalyst] Add forgotten PNSE and ActiveIssue

* [MacCatalyst][libraries] Coalesce MacCatalyst into iOS tvOS SkipOnPlatform
Co-authored-by: NMitchell Hwang <mitchell.hwang@microsoft.com>

The old URL didn't show the template anymore, just a generic GitHub page. Linking to the raw URL so `<!-- -->` comments are visible.

[main] Update dependencies from dotnet/emsdk

* extend FileStreamOptions with BufferSize

* allow to disable the buffering by setting bufferSize to 0

* Apply suggestions from code review
Co-authored-by: NDavid Cantú <dacantu@microsoft.com>

* Remove the use of IsPartialFacadeAssembly in refererences

This flag requires assembly-re-writing to replace type-defs in reference
assemblies with type forwards, when the same type exists in references.

We've pretty much exclusively used this on .NETFramework, since it's
not friendly to source build (CCI isn't part of source build).
.NETFramework isn't going to be changing so it doesn't save us much
to generate these typeforwards in the build.

We also used these to make sure the netstandard surface area was
compatible with .NETFramework facades (we'd use the pre-rewritten
reference assemblies for contract), but this need goes away now that we
have package validation based APICompat that compares netstandard refs
to net4x facades.

* Fix some projects I missed after changing naming convention

* Fixup another project

* Fix build of System.System.Threading.AccessControl

* Adding a section to ref-source docs on .NETFramework facades

* Address feedback

Co-authored-by: NJan Kotas <jkotas@microsoft.com>

* refactor lsra

* Add missing return condition

* Minor cleanup

- summary docs
- Removed DEFAULT_ORDER
- Added order seq ID

* jit format

* fix linux build

* review feedback

* Remove TODO

If we have PGO data and the dominant non-default switch case has more than
55% of the profile, add an explicit test for that case upstream of the switch.

We don't see switches all that often anymore as CSC is quite aggressive about
turning them into if-then-else trees, but they still show up in the async
methods.

* [wasm] Split _WasmNativeBuild into separate targets, as steps

- this gives us more control over the flow, and will be useful for
  dependency checking (future work)

* [wasm] WasmApp.targets: Decouple aot compilation from native relinking

* [wasm] Convert emcc flags from property to item, and use rsp files

The default arguments are still from `emcc-flags.txt`, which will get
converted into a rsp file and used with this, in a future PR.

* cleanup

* [wasm] Add new properties to explicitly control optimization level used

.. for compiling native files, and linking.

`$(WasmLinkOptimizationFlag)`, and `$(WasmCompileOptimizationFlag)`

note: right now `emcc-flags.txt` has flags already specified, but that
will go away in favor of only these flags (future work)

* [wasm] Add new properties to specify extra emcc flags

`$(EmccExtraLDFlags)`, `$(EmccExtraCFlags)`

* dummy

* Remove From header validation from System.Net.Http

The From header is not commonly used and this logic adds a decent amount of code to System.Net.Http that can't be trimmed.

Fix #52664

* Use OperatingSystem APIs instead of RuntimeInformation in more places

These are recommended instead of the older APIs.

* PR feedback

* [build] Define NO_UNALIGNED_ACCESS for 32-bit arm platforms

Possibly related to crashes on Android like this:

```
05-18 10:59:07.466 17076 17076 F libc    : Fatal signal 7 (SIGBUS), code 1 (BUS_ADRALN), fault addr 0xb9c95a41 in tid 17076 (simplehellomaui), pid 17076 (simplehellomaui)
05-18 10:59:07.501 17104 17104 I crash_dump32: obtaining output fd from tombstoned, type: kDebuggerdTombstone
05-18 10:59:07.502   989   989 I tombstoned: received crash request for pid 17076
05-18 10:59:07.503 17104 17104 I crash_dump32: performing dump of process 17076 (target tid = 17076)
05-18 10:59:07.512 17104 17104 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
05-18 10:59:07.512 17104 17104 F DEBUG   : Build fingerprint: 'google/crosshatch/crosshatch:11/RQ2A.210405.005/7181113:user/release-keys'
05-18 10:59:07.512 17104 17104 F DEBUG   : Revision: 'MP1.0'
05-18 10:59:07.512 17104 17104 F DEBUG   : ABI: 'arm'
05-18 10:59:07.515 17104 17104 F DEBUG   : Timestamp: 2021-05-18 10:59:07+0200
05-18 10:59:07.515 17104 17104 F DEBUG   : pid: 17076, tid: 17076, name: simplehellomaui  >>> com.microsoft.simplehellomaui <<<
05-18 10:59:07.515 17104 17104 F DEBUG   : uid: 10364
05-18 10:59:07.515 17104 17104 F DEBUG   : signal 7 (SIGBUS), code 1 (BUS_ADRALN), fault addr 0xb9c95a41
05-18 10:59:07.515 17104 17104 F DEBUG   :     r0  bb4a5cd0  r1  b9c95a49  r2  00000000  r3  e94c7520
05-18 10:59:07.515 17104 17104 F DEBUG   :     r4  0000000c  r5  00000000  r6  ff843c50  r7  ff843e70
05-18 10:59:07.515 17104 17104 F DEBUG   :     r8  b69547f8  r9  e99eac50  r10 00000000  r11 00000021
05-18 10:59:07.515 17104 17104 F DEBUG   :     ip  e94c74f0  sp  ff843c48  lr  bb31e0dd  pc  bb3a4d24
05-18 10:59:07.531   709   709 E Layer   : [Surface(name=Task=1)/@0x52e6b1a - animation-leash#0] No local sync point found
05-18 10:59:07.532   709   709 E Layer   : [Surface(name=Task=1571)/@0x9c90165 - animation-leash#0] No local sync point found
05-18 10:59:07.706 17104 17104 F DEBUG   : backtrace:
05-18 10:59:07.707 17104 17104 F DEBUG   :       #00 pc 000ddd24  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mono_method_to_ir+9232) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #01 pc 000d7777  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (inline_method+622) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #02 pc 000ec0a3  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mono_method_to_ir+67470) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #03 pc 000cda6d  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mini_method_compile+2264) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #04 pc 000cf413  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mono_jit_compile_method_inner+50) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #05 pc 000d1d7f  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mono_jit_compile_method_with_opt+1766) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #06 pc 0012d94d  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (common_call_trampoline+832) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #07 pc 0012d5cb  /data/app/~~J4DFQ3c1v2YGrEurX7TNjg==/com.microsoft.simplehellomaui-_jGGPiZpZ3yT-QCTNDcgvQ==/lib/arm/libmonosgen-2.0.so (mono_magic_trampoline+62) (BuildId: d0a4e41a500357a621884b64f6ca8533b62a664b)
05-18 10:59:07.707 17104 17104 F DEBUG   :       #08 pc 0000006a <anonymous:b7986000>
```

* move to host/target sections

The octokit client we get from @actions/github recently changed their API.

* Avoid calling result.ToString() when the Assert condition is not met

* handle other asserts

* Update Random.cs
Co-authored-by: NJan Kotas <jkotas@microsoft.com>

We decided that we need to rule out the Windows Firewall as a cause for further failure types documented in #42211.

close #47163

If the solver wants to set the edge weight below zero, set it to
zero if within slop, or disallow if not.

Addresses assert seen in #52785.

It fails on Mono in the runtime-staging pipeline: https://github.com/dotnet/runtime/issues/52910

* Fix OfficialBuildId property passing down to scripts

Regressed with https://github.com/dotnet/runtime/commit/4267d564affb062f934126e285aed9d9608adfee

* Add support for building Mac Catalyst offsets, and use to create AOT compiler nupkgs

[main] Update dependencies from mono/linker

Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-optimization build 20210517.7 (#52901)

optimization.linux-x64.MIBC.Runtime , optimization.windows_nt-x64.MIBC.Runtime , optimization.windows_nt-x86.MIBC.Runtime , optimization.PGO.CoreCLR
 From Version 1.0.0-prerelease.21266.3 -> To Version 1.0.0-prerelease.21267.7
Co-authored-by: Ndotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>