Right now they're `gnueabihf` and `gnueabi`, but when adding new platforms like
musl on ARM it's unfortunate to have to test for all three (`musl`, `musleabi`,
and `musleabihf`). This PR switches everything currently to `gnu`, and the new
musl targets can also use `musl` when they land.

Closes #33244

"cc" is already the default.

Android's [armeabi-v7a ABI][1] guarantees at least VFPv3-d16 hardware FPU
support, so Rust should include this in the default features for the
arm-linux-androideabi target.

[1]: https://developer.android.com/ndk/guides/abis.html

This commit applies all stabilizations, renamings, and deprecations that the
library team has decided on for the upcoming 1.9 release. All tracking issues
have gone through a cycle-long "final comment period" and the specific APIs
stabilized/deprecated are:

Stable

* `std::panic`
* `std::panic::catch_unwind` (renamed from `recover`)
* `std::panic::resume_unwind` (renamed from `propagate`)
* `std::panic::AssertUnwindSafe` (renamed from `AssertRecoverSafe`)
* `std::panic::UnwindSafe` (renamed from `RecoverSafe`)
* `str::is_char_boundary`
* `<*const T>::as_ref`
* `<*mut T>::as_ref`
* `<*mut T>::as_mut`
* `AsciiExt::make_ascii_uppercase`
* `AsciiExt::make_ascii_lowercase`
* `char::decode_utf16`
* `char::DecodeUtf16`
* `char::DecodeUtf16Error`
* `char::DecodeUtf16Error::unpaired_surrogate`
* `BTreeSet::take`
* `BTreeSet::replace`
* `BTreeSet::get`
* `HashSet::take`
* `HashSet::replace`
* `HashSet::get`
* `OsString::with_capacity`
* `OsString::clear`
* `OsString::capacity`
* `OsString::reserve`
* `OsString::reserve_exact`
* `OsStr::is_empty`
* `OsStr::len`
* `std::os::unix::thread`
* `RawPthread`
* `JoinHandleExt`
* `JoinHandleExt::as_pthread_t`
* `JoinHandleExt::into_pthread_t`
* `HashSet::hasher`
* `HashMap::hasher`
* `CommandExt::exec`
* `File::try_clone`
* `SocketAddr::set_ip`
* `SocketAddr::set_port`
* `SocketAddrV4::set_ip`
* `SocketAddrV4::set_port`
* `SocketAddrV6::set_ip`
* `SocketAddrV6::set_port`
* `SocketAddrV6::set_flowinfo`
* `SocketAddrV6::set_scope_id`
* `<[T]>::copy_from_slice`
* `ptr::read_volatile`
* `ptr::write_volatile`
* The `#[deprecated]` attribute
* `OpenOptions::create_new`

Deprecated

* `std::raw::Slice` - use raw parts of `slice` module instead
* `std::raw::Repr` - use raw parts of `slice` module instead
* `str::char_range_at` - use slicing plus `chars()` plus `len_utf8`
* `str::char_range_at_reverse` - use slicing plus `chars().rev()` plus `len_utf8`
* `str::char_at` - use slicing plus `chars()`
* `str::char_at_reverse` - use slicing plus `chars().rev()`
* `str::slice_shift_char` - use `chars()` plus `Chars::as_str`
* `CommandExt::session_leader` - use `before_exec` instead.

Closes #27719
cc #27751 (deprecating the `Slice` bits)
Closes #27754
Closes #27780
Closes #27809
Closes #27811
Closes #27830
Closes #28050
Closes #29453
Closes #29791
Closes #29935
Closes #30014
Closes #30752
Closes #31262
cc #31398 (still need to deal with `before_exec`)
Closes #31405
Closes #31572
Closes #31755
Closes #31756

The path `/etc/rustc/` is not the default last entry in
RUST_TARGET_PATH. This was in RFC131 but was never implemented in rustc
so it was removed as part of #31117 and rust-lang/rfcs#1473.
Signed-off-by: NDoug Goldstein <cardoe@cardoe.com>

cc #32818

Automated conversion using the untry tool [1] and the following command:

```
$ find -name '*.rs' -type f | xargs untry
```

at the root of the Rust repo.

[1]: https://github.com/japaric/untry

The `data-layout` field  was made optional in 958d5638. The `os` field is always required.

Removes all unstable and deprecated APIs prior to the 1.8 release. All APIs that
are deprecated in the 1.8 release are sticking around for the rest of this
cycle.

Some notable changes are:

* The `dynamic_lib` module was moved into `rustc_back` as the compiler still
  relies on a few bits and pieces.
* The `DebugTuple` formatter now special-cases an empty struct name with only
  one field to append a trailing comma.

Similarly to #31629 where an i586-unknown-linux-gnu target was added, there is
sometimes a desire to compile for x86 Windows as well where SSE2 is disabled.
This commit mirrors the i586-unknown-linux-gnu target and simply adds a variant
for Windows as well.

This is motivated by a recent [Gecko bug][ff] where crashes were seen on 32-bit
Windows due to users having CPUs that don't support SSE2 instructions. It was
requested that we could have non-SSE2 builds of the standard library available
so they could continue to use vanilla releases and nightlies.

[ff]: https://bugzilla.mozilla.org/show_bug.cgi?id=1253202

A whole bunch of stuff gets folded into struct handling! Plus, removes
an ugly hack from trans and accidentally fixes a bug with constructing
ranges from references (see later commits with tests).

.copy_from_slice() does the same job of .clone_from_slice(), but the
former is explicitly for Copy elements and calls `memcpy` directly, and
thus is it efficient without optimization too.

The initial purpose is to workaround the LLVM bug
https://llvm.org/bugs/show_bug.cgi?id=26554 for OpenBSD.

By default, the `cpu' is defined to `generic`. But with a 64bit
processor, the optimization for `generic` will use invalid asm code as
NOP (the generated code for NOP isn't a NOP).

According to #20777, "x86-64" is the right thing to do for x86_64
builds.

Closes: #31363

When building with Cargo we need to detect `feature = "jemalloc"` to enable
jemalloc, so propagate this same change to the build system to pass the right
`--cfg` argument.

These describe the structure of all our crate dependencies.

It's already enabled for i686-pc-windows-gnu.