[llvm] [llvm][macho] Support the LC_TARGET_TRIPLE load command (PR #210276)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/38743

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: MC/MachO/target-triple.s' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
split-file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\MC\MachO\target-triple.s Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp
# executed command: split-file 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\MC\MachO\target-triple.s' 'Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp'
# note: command had no output on stdout or stderr
# RUN: at line 3
z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe -triple arm64-apple-macos Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp/target-triple.s | z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp/target-triple.s
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe' -triple arm64-apple-macos 'Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp/target-triple.s'
# .---command stderr------------
# | z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe: error: unable to get target for 'arm64-apple-macos', see --version and --triple.
# `-----------------------------
# error: command failed with exit status: 1
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe' 'Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp/target-triple.s'
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\build\test\MC\MachO\Output\target-triple.s.tmp/target-triple.s
# `-----------------------------
# error: command failed with exit status: 2

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/210276