[clang] Fixes and closes #53952. Setting the ASTHasCompilerErrors member variable correctly based on the PP diagnostics. (PR #68127)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

The fix does not look correct but perhaps someone else will have more insight.

https://github.com/llvm/llvm-project/pull/68127