[clang] [Lexer] Prevent hitting the file system for ASTReader tokens (PR #192492)

[via cfe-commits]

lucasvallejoo wrote:

Good catch! I accidentally ran clang-format on the entire Lexer.cpp file instead of just my patch, which introduced a lot of formatting noise. I've reset the file, manually formatted the 4 lines, and force-pushed the clean diff. Thanks for pointing it out!

https://github.com/llvm/llvm-project/pull/192492