[clang] [alpha.webkit.MemoryUnsafeCastChecker] Don't emit a warning for const_cast (PR #231833)

[Balázs Benics via cfe-commits]

https://github.com/steakhal approved this pull request.

LGTM.
I had a tiny rename suggestion.
I also believe that the PR title does not represent this change. I think the change is about canonical decls and redecls - and has nothing to do with const_casts.

https://github.com/llvm/llvm-project/pull/231833