Windows CI is flaky

[fmayer]

This is the second time I have seen this in a Windows presubmit run:

llvm-lit.py: C:\_work\llvm-project\llvm-project\llvm\utils\lit\lit\llvm\config.py:280: fatal: Could not run process ['c:\\_work\\llvm-project\\llvm-project\\build\\bin\\clang.exe', '-print-file-name=include']
  [6118/6127] Linking CXX executable bin\clang-check.exe
  FAILED: tools/clang/tools/extra/CMakeFiles/check-clang-tools 

This is the run: https://github.com/llvm/llvm-project/actions/runs/16231417535/job/45834859069?pr=148310

[boomanaiden154]

This is #145703.

From offline discussion this was happening in a stacked PR and the fix had not yet made it into the base branch. It should be fixed by rebasing everything.