[clang] [clang][Lex] Use getBufferName() in isInPredefinedFile() (PR #141490)

[Timm Baeder via cfe-commits]

tbaederr wrote:

http://llvm-compile-time-tracker.com/compare.php?from=0917b0525b49f0d8fe64e26947449c55db5fc00a&to=65f3db15d875c7279c95afdd2a9221ec43dc61b4&stat=instructions:u

https://github.com/llvm/llvm-project/pull/141490