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

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

Please also be sure to add enough information to the PR summary to explain why the changes are needed (the summary becomes the commit message).

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