[llvm] Reapply [MachO] Move getArchTriple implementation..." with fixes. (PR #161949)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `polly-x86_64-linux-shared` running on `polly-x86_64-gce2` while building `llvm` at step 5 "build".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/97/builds/8752

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

```
Step 5 (build) failure: 'ninja' (failure)
...
[2239/4520] Linking CXX shared library lib/libLLVMDWP.so.22.0git
[2240/4520] Creating library symlink lib/libLLVMDWP.so
[2241/4520] Linking CXX shared library lib/libLLVMJITLink.so.22.0git
[2242/4520] Creating library symlink lib/libLLVMJITLink.so
[2243/4520] Linking CXX shared library lib/libLLVMRuntimeDyld.so.22.0git
[2244/4520] Creating library symlink lib/libLLVMRuntimeDyld.so
[2245/4520] Linking CXX shared library lib/libLLVMProfileData.so.22.0git
[2246/4520] Creating library symlink lib/libLLVMProfileData.so
[2247/4520] Linking CXX shared library lib/libLLVMTextAPIBinaryReader.so.22.0git
[2248/4520] Linking CXX shared library lib/libLLVMCoverage.so.22.0git
FAILED: lib/libLLVMCoverage.so.22.0git 
: && /usr/bin/c++ -fPIC -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wl,-z,defs -Wl,-z,nodelete -fuse-ld=lld -Wl,--color-diagnostics   -Wl,--gc-sections -shared -Wl,-soname,libLLVMCoverage.so.22.0git -o lib/libLLVMCoverage.so.22.0git lib/ProfileData/Coverage/CMakeFiles/LLVMCoverage.dir/CoverageMapping.cpp.o lib/ProfileData/Coverage/CMakeFiles/LLVMCoverage.dir/CoverageMappingWriter.cpp.o lib/ProfileData/Coverage/CMakeFiles/LLVMCoverage.dir/CoverageMappingReader.cpp.o  -Wl,-rpath,"\$ORIGIN/../lib:/home/worker/buildbot-workers/polly-x86_64-gce2/rundir/llvm.obj/lib:"  lib/libLLVMProfileData.so.22.0git  lib/libLLVMObject.so.22.0git  lib/libLLVMCore.so.22.0git  lib/libLLVMTargetParser.so.22.0git  lib/libLLVMSupport.so.22.0git  -Wl,-rpath-link,/home/worker/buildbot-workers/polly-x86_64-gce2/rundir/llvm.obj/lib && :
ld.lld: error: undefined symbol: llvm::MachO::getArchTriple(unsigned int, unsigned int, char const**, char const**)
>>> referenced by CoverageMappingReader.cpp
>>>               lib/ProfileData/Coverage/CMakeFiles/LLVMCoverage.dir/CoverageMappingReader.cpp.o:(llvm::coverage::BinaryCoverageReader::create(llvm::MemoryBufferRef, llvm::StringRef, llvm::SmallVectorImpl<std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer> > >&, llvm::StringRef, llvm::SmallVectorImpl<llvm::ArrayRef<unsigned char> >*) (.localalias))
>>> referenced by CoverageMappingReader.cpp
>>>               lib/ProfileData/Coverage/CMakeFiles/LLVMCoverage.dir/CoverageMappingReader.cpp.o:(llvm::coverage::BinaryCoverageReader::create(llvm::MemoryBufferRef, llvm::StringRef, llvm::SmallVectorImpl<std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer> > >&, llvm::StringRef, llvm::SmallVectorImpl<llvm::ArrayRef<unsigned char> >*) (.localalias))
collect2: error: ld returned 1 exit status
[2249/4520] Building CXX object tools/llvm-config/CMakeFiles/llvm-config.dir/llvm-config.cpp.o
[2250/4520] Linking CXX shared library lib/libLLVMAnalysis.so.22.0git
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/161949