[lld] [LLD][COFF] Implement support for hybrid IAT on ARM64X (PR #124189)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

Note that you have one failing test on the Windows CI job (on buildkit) https://buildkite.com/llvm-project/github-pull-requests/builds/140034#019494f4-99b5-464b-b932-d46371db3949:

```
c:\ws\src\build\bin\lld-link.exe -machine:arm64x -dll -noentry -out:test-n12.dll loadconfig-arm64.obj loadconfig-arm64ec.obj           func12-arm64.obj imp-arm64x.lib
# executed command: 'c:\ws\src\build\bin\lld-link.exe' -machine:arm64x -dll -noentry -out:test-n12.dll loadconfig-arm64.obj loadconfig-arm64ec.obj func12-arm64.obj imp-arm64x.lib
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
# | Exception Code: 0xC0000005
# | Exception Code: 0xC0000005
# | Exception Code: 0xC0000005
# | #0 0x00007ffb7b36180a (C:\Windows\SYSTEM32\VCRUNTIME140.dll+0x1180a)
# | #1 0x00007ff7c9229fef (c:\ws\src\build\bin\lld-link.exe+0x3e49fef)
# | #2 0x00007ff7c9229f7d (c:\ws\src\build\bin\lld-link.exe+0x3e49f7d)
# | #3 0x00007ff7c922a887 (c:\ws\src\build\bin\lld-link.exe+0x3e4a887)
# | #4 0x00007ff7c92291b9 (c:\ws\src\build\bin\lld-link.exe+0x3e491b9)
# | #5 0x00007ffb809b268a (C:\Windows\System32\ucrtbase.dll+0x2268a)
# | #6 0x00007ffb82d87ac4 (C:\Windows\System32\KERNEL32.DLL+0x17ac4)
# | #7 0x00007ffb90b3a4e1 (C:\Windows\SYSTEM32\ntdll.dll+0x5a4e1)
# `-----------------------------
# error: command failed with exit status: 0xc0000005

[...]

Failed Tests (1):
  lld :: COFF/arm64x-import.test
```

https://github.com/llvm/llvm-project/pull/124189