[compiler-rt] [compiler-rt] freadlink fix 2 for #83679. (PR #110372)

[David CARLIER via llvm-commits]

devnexen wrote:

Normally 

```cmake
if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
```

should work, the issues lies on the missing quotes for the string.

https://github.com/llvm/llvm-project/pull/110372