[runtime] Avoid loading ThreadAbortException class on netcore.

This gives us a single method that controls most of the jit's phase behavior.
Largely a manual inline, though I updated some comments and changed one assert.

Follow up from #1309; also see #2109.

Need to also report the hidden return buffer pointer as GC live, in case it
happens to refer to a heap location (method invoked via reflection).

Also did some minor cleanup; we weren't using `returnsGCr` in `emitEndCodeGen`
and we were munging return value liveness unnecessarily when not emitting
a profiler leave hook.

Closes #1971.

* Refactor CMake system to allow cross OS DAC compile

Add CLR_CMAKE_HOST_OS

Add rules to determine which cross OS combinations are valid

Make add_definitions depend on TARGET OS properties. Wherever reasonable 
make C++ defines depend on runtime target rather than host.

Initial CMAKE build system support for Mono.

Matches what we do for uninstatiated generic types - no need to look at generic parameters.

* Remove date number from dev build version

* Set Library assembly version back to 5.0.0.0

* Use default assembly version in versions.props and fix package testing

* Add missed change to define AssemblyVersion to match MajorVersion.MinorVersion.0.0 in the root

* Don't change AssemblyVersions in installer, leave as it was

* Fix installer tests

* Move AssemblyVersion for installer test assets to right place
Co-authored-by: NSantiago Fernandez Madero <safern@microsoft.com>

* corefx => runtime

* Update adding-api-guidelines.md

* Update adding-api-guidelines.md

* Recognize the `Vector128/256.AsVector*` methods as intrinsic

* Ensure we normalize the struct handle for S.Numerics to S.R.Intrinsic vector conversions

* Marking the Vector128/256.As* methods as intrinsic

* Don't handle AsVector2 or AsVector3 as intrinsic right now

Issue was fixed but test was not enabled.

Follow-up to https://github.com/dotnet/runtime/pull/1934

Also disables one test that seems to be flaky on Mono.

* Add COMPlus_DiagnosticsServerTransportPath
* allows users to specify a location for the Diagnostics Server

* Add alpinedac & linuxdac build options

- In some cases, I deleted ActiveIssues associated with issues where the problem was supposedly fixed.  We'll see.
- In some cases, I deleted test cases entirely, e.g. where the corresponding issue said effectively "we'll live with the behavior" or "another repo is responsible for this now" (paraphrasing), or where the tests were initially added to the repo years ago already disabled and against bug numbers from some old bug database.
- In some cases, I replaced the link with the correct one.
- In some cases, I re-opened closed issues.

* Fix assert 'treeWithCall == call'

This assert was occurring when we have:
- a potential optimistic tail call
- of a function that returns a ref type
- that is also an inline candidate
- whose inline is rejected
- with `COMPlus_JitGCChecks` stress mode that injects a
call to `CORINFO_HELP_CHECK_OBJ` at the `RETURN`
- where we decide to go ahead with the optimistic tailcall
but it is no longer in legal tailcall position.

To fix, simply disallow a tailcall if we are doing
`COMPlus_JitGCChecks` in a function with a ref type return, that
would have inserted the problemmatic call.

Fixes #1821

* Fix formatting

* Make sure CoreCLRArtifactsPath/MonoArtifactsPath has trailing slash

Addresses the official build break caused by the Mono CI PR.

Fixes https://github.com/dotnet/runtime/issues/2053

* Handle empty RuntimeArtifactsPath

Fixes #483. Structs with pointer-typed fields are blittable.

After #1866 we no longer have to worry about the recursion because the code path that recursed into pointed-to types was deleted.

Remove "handles" from System.Threading.Semaphore.
Co-Authored-By: NJay Krell <jaykrell@microsoft.com>

* begining -> beginning

* paramterized -> parameterized

* folow -> follow

* occurance -> occurrence

* Fix bad changes

* Apply suggestion + minor space fix

* Fix for issue #1740

U+0085 not recognised as a newline character in CSharpCodeGenerator.cs

Fix $1740

* Fix for issue #1740

U+0085 not recognised as a newline character in CSharpCodeGenerator.cs

* Fix for issue #1740

U+0085 not recognised as a newline character in CSharpCodeGenerator.cs
This change fixes a previous test that incorrectly causes the character to be forced out of being in unicode format.

* Stop the changes from #1740 on the .Net Framework as per #1913

Read #1913 for why, view PR #1853 and #1740 also.

[debugger] Native thread not executing managed code considered as terminated 

Fixes mono/mono#18417

[jit] Compute the instance size/alignment correctly for gshared types whose constraint is a generic valuetype. (#2034)

Fixes mono/mono#18455

* Add workaround for ILLinker stripping COM interop details

Fixes #1264

* Correct version of the fix

It's not needed in dotnet/runtime.

* Improve markdown file

* Revert the ol to ul change