[clang] [Clang] add emit -Wignored-base-class-qualifiers diagnostic for cv-qualified base classes (PR #132116)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

Precommit CI failure on Linux appears to be unrelated, so landing the changes (I'll watch the bots in case it was related somehow).

https://github.com/llvm/llvm-project/pull/132116