[clang] [NFC][analyzer] Conversion to CheckerFamily: RetainCountChecker (PR #152138)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

> I'm not too interested reviewing this.

Completely understandable, I'm uploading quite many boring cleanup commits nowdays :) I'm adding you as a reviewer on them to give you an opportunity to object if you see any glaring issues, but I don't expect you to dig into the details if you are not interested / don't have time for them.

By the way thanks for the inspiration that led to creating this new CheckerFamily framework, it's much more elegant than my earlier "enum + array of checker names" approach. I'm close to finishing this conversion, and I hope that I can do some more substantial change (probably bringing the ReturnPtr and cstring.OutOfBound checkers out of alpha state).

https://github.com/llvm/llvm-project/pull/152138