[Darwin] [compiler-rt] Normalize DYLD_LIBRARY_PATH to workaround LD bug (#175685)

There is an issue in certain versions of LD which causes the wrong
libLTO to be used if the DYLD_LIBRARY_PATH is not normalized.

Will fix these failures:
```
AddressSanitizer-x86_64-darwin.TestCases/Darwin.odr-lto.cpp
AddressSanitizer-x86_64h-darwin.TestCases/Darwin.odr-lto.cpp
```

https://green.lab.llvm.org/job/llvm.org/job/clang-stage1-cmake-RA-incremental/13428/

rdar://168024431

GitOrigin-RevId: 12ecbfb59b865ab98d1cecd78282e640420617c7
1 file changed