[clang] [CodeGen] Fix new-delete-type-mismatch in ~CodeGenTypes() (PR #135787)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Please also make the unused "operator delete" in CGFunctionInfo.h deleted, since it shouldn't have any callers.

I think this never actually led to a real issue because of that operator delete... it calls the right deallocation function even if it's technically undefined.  So the only way to spot an issue would be a sanitizer that specifically checks for this.  But I'm happy to "fix" this anyway.

https://github.com/llvm/llvm-project/pull/135787