std.Target.Cpu.Arch: Remove the `aarch64_32` tag.

This is a misfeature that we inherited from LLVM:

* https://reviews.llvm.org/D61259
* https://reviews.llvm.org/D61939

(`aarch64_32` and `arm64_32` are equivalent.)

I truly have no idea why this triple passed review in LLVM. It is, to date, the
*only* tag in the architecture component that is not, in fact, an architecture.
In reality, it is just an ILP32 ABI for AArch64 (*not* AArch32).

The triples that use `aarch64_32` look like `aarch64_32-apple-watchos`. Yes,
that triple is exactly what you think; it has no ABI component. They really,
seriously did this.

Since only Apple could come up with silliness like this, it should come as no
surprise that no one else uses `aarch64_32`. Later on, a GNU ILP32 ABI for
AArch64 was developed, and support was added to LLVM:

* https://reviews.llvm.org/D94143
* https://reviews.llvm.org/D104931

Here, sanity seems to have prevailed, and a triple using this ABI looks like
`aarch64-linux-gnu_ilp32` as you would expect.

As can be seen from the diffs in this commit, there was plenty of confusion
throughout the Zig codebase about what exactly `aarch64_32` was. So let's just
remove it. In its place, we'll use `aarch64-watchos-ilp32`,
`aarch64-linux-gnuilp32`, and so on. We'll then translate these appropriately
when talking to LLVM. Hence, this commit adds the `ilp32` ABI tag (we already
have `gnuilp32`).

1 files changed, 0 insertions, 1 deletions

diff --git a/src/Zcu.zig b/src/Zcu.zig
index 3396728edd..c644dcce64 100644
--- a/src/Zcu.zig
+++ b/src/Zcu.zig
@@ -3284,7 +3284,6 @@ pub fn atomicPtrAlignment(
 
         .aarch64,
         .aarch64_be,
-        .aarch64_32,
         => 128,
 
         .x86_64 => if (std.Target.x86.featureSetHas(target.cpu.features, .cx16)) 128 else 64,