[BUG] cmake generate fails with msvc and clang-cl

**Describe the bug**
A clear and concise description of what the bug is.

cmake fails at
https://github.com/google/benchmark/blob/main/CMakeLists.txt#L298

when using cmake on msvc with clang-cl settings
https://learn.microsoft.com/en-us/cpp/build/clang-support-cmake?view=msvc-170

**System**
Which OS, compiler, and compiler version are you using:
- OS: Windows
- Compiler and version:
```
1> [CMake] CMAKE_C_COMPILER= C:/PROGRAM FILES/MICROSOFT VISUAL STUDIO/2022/COMMUNITY/VC/Tools/Llvm/x64/bin/clang-cl.exe
1> [CMake] CMAKE_CXX_COMPILER= C:/PROGRAM FILES/MICROSOFT VISUAL STUDIO/2022/COMMUNITY/VC/Tools/Llvm/x64/bin/clang-cl.exe
```

**To reproduce**
Steps to reproduce the behavior:
1. sync to commit ...
2. cmake/bazel...
3. make ...
4. See error

**Expected behavior**
A clear and concise description of what you expected to happen.

**Screenshots**
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**Additional context**
Add any other context about the problem here.