[llvm] [BOLT] Enable standalone build (PR #97130)

[via llvm-commits]

gulfemsavrun wrote:

We started seeing a build failure on our Mac toolchain builders after this patch:
```
v408/6105](55) Performing build step for 'bolt_rt'
FAILED: tools/bolt/bolt_rt-stamps/bolt_rt-build /Volumes/Work/s/w/ir/x/w/llvm_build/tools/bolt/bolt_rt-stamps/bolt_rt-build 
cd /Volumes/Work/s/w/ir/x/w/llvm_build/tools/bolt/bolt_rt-bins && /Volumes/Work/s/w/ir/x/w/cipd_tool/fuchsia/third_party/cmake/72c014f0086372a2bab7ed771e2ed942d6122d94331d19c95566bb25d2f962ff/bin/cmake --build .
[1/6](2) Building CXX object CMakeFiles/bolt_rt_hugify.dir/hugify.cpp.o
[2/6](2) Linking CXX static library lib/libbolt_rt_hugify.a
/Volumes/Work/s/w/ir/cache/macos_sdk/XCode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: lib/libbolt_rt_hugify.a(hugify.cpp.o) has no symbols
[3/6](1) Building CXX object CMakeFiles/bolt_rt_instr.dir/instr.cpp.o
[4/6](1) Building CXX object CMakeFiles/bolt_rt_instr_osx.dir/instr.cpp.o
[5/6](1) Linking CXX static library lib/libbolt_rt_instr.a
[6/6](0) Linking CXX static library /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a
FAILED: /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a 
: && /Volumes/Work/s/w/ir/x/w/cipd_tool/fuchsia/third_party/cmake/72c014f0086372a2bab7ed771e2ed942d6122d94331d19c95566bb25d2f962ff/bin/cmake -E rm -f /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a && /usr/bin/ar qc /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a  CMakeFiles/bolt_rt_instr_osx.dir/instr.cpp.o && /Volumes/Work/s/w/ir/x/w/cipd/bin/llvm-ranlib /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a && /Volumes/Work/s/w/ir/x/w/cipd_tool/fuchsia/third_party/cmake/72c014f0086372a2bab7ed771e2ed942d6122d94331d19c95566bb25d2f962ff/bin/cmake -E touch /Volumes/Work/s/w/ir/x/w/llvm_build/lib/libbolt_rt_instr_osx.a && cd /Volumes/Work/s/w/ir/x/w/llvm_build/tools/bolt/bolt_rt-bins && /Volumes/Work/s/w/ir/x/w/cipd_tool/fuchsia/third_party/cmake/72c014f0086372a2bab7ed771e2ed942d6122d94331d19c95566bb25d2f962ff/bin/cmake -E copy /Volumes/Work/s/w/ir/x/w/llvm_build/tools/bolt/bolt_rt-bins/lib/libbolt_rt_instr_osx.a /Volumes/Work/s/w/ir/x/w/llvm_build/./lib
Error copying file "/Volumes/Work/s/w/ir/x/w/llvm_build/tools/bolt/bolt_rt-bins/lib/libbolt_rt_instr_osx.a" to "/Volumes/Work/s/w/ir/x/w/llvm_build/./lib".
ninja: build stopped: subcommand failed.
```

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-mac-x64/b8741423380032029377/overview

https://logs.chromium.org/logs/fuchsia/buildbucket/cr-buildbucket/8741423380032029377/+/u/clang/build/stdout

https://github.com/llvm/llvm-project/pull/97130