Configuring compiler-rt fails when C compiler path contains spaces

The following error is emitted during configuration:
```
CMake Error at cmake/Modules/CheckSectionExists.cmake:72 (message):
Call Stack (most recent call first):
lib/builtins/CMakeLists.txt:1025 (check_section_exists)
```

This occurs because all spaces in `test_compile_command` are replaced with `;` [here](https://github.com/llvm/llvm-project/blob/6b040b0dee9cb8b38e56dbcb7e51182a62703e05/compiler-rt/cmake/Modules/CheckSectionExists.cmake#L61). It breaks the build with a default installation of LLVM on Windows (install path `C:\Program Files\LLVM`).

Start in compiler-rt/cmake/Modules/CheckSectionExists.cmake around line 61, then follow its call from lib/builtins/CMakeLists.txt:1025. Reproduce configuration with an LLVM installation under C:\Program Files\LLVM and inspect how test_compile_command is handled. Done means configuration completes without the reported error when the compiler path contains spaces.

Written by the indexing model from the issue text.