[clang] [analyzer] Fix false positive for mutexes inheriting mutex_base (PR #106240)

[Balazs Benics via cfe-commits]

https://github.com/steakhal requested changes to this pull request.

Uh that FN seems really bad. Have you measured this change?
Can we relax the canonicalization to only unwrap base class regions, or only apply to classes within the stdlib?

https://github.com/llvm/llvm-project/pull/106240