[clang] Implement -Wcast-qual for C++
Summary:
This way, the behavior of that warning flag
more closely resembles that of GCC.
Do note that there is at least one false-negative (see FIXME in tests).
Fixes PR4802.
Testing:
```
ninja check-clang-sema check-clang-semacxx
```
Reviewers: dblaikie, majnemer, rnk
Reviewed By: dblaikie, rnk
Subscribers: cfe-commits, alexfh, rnk
Differential Revision: https://reviews.llvm.org/D33102
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@305147
91177308-0d34-0410-b5e6-
96231b3b80d8
projects / clang / commit