Revert "Fixes and closes #53952. Setting the ASTHasCompilerErrors member...

Revert "Fixes and closes #53952. Setting the ASTHasCompilerErrors member variable correctly based on the PP diagnostics. (#68127)"

This reverts commit a50e63b3.

With clang-14.0.6 as the host compiler, I'm getting:

ld.lld: error: undefined symbol: clang::ASTWriter::WriteAST(clang::Sema&, llvm::StringRef, clang::Module*, llvm::StringRef, bool, bool)
>>> referenced by ASTUnit.cpp
>>>               ASTUnit.cpp.o:(clang::ASTUnit::serialize(llvm::raw_ostream&)) in archive lib/libclangFrontend.a