[clang] [clang] Optimize SourceManager.getSpellingLocSlowCase and SourceManager.getFileLocSlowCase (PR #164269)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> Optimize implementations of `getSpellingLocSlowCase` and `getFileLocSlowCase` by inlining called methods to avoid repeated calls to `getSLocEntry` and `getFileID`.
> 
> #160667

I think the patch summary and title should be updated, this isn't so much about optimization as it is fixing a bug with debug info, right?

https://github.com/llvm/llvm-project/pull/164269