-fsanitize=vptr warnings on bad static types in dynamic_cast and typeid

...when such an operation is done on an object during con-/destruction.

This is the cfe part of a patch covering both cfe and compiler-rt.

Differential Revision: https://reviews.llvm.org/D40295



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321519 91177308-0d34-0410-b5e6-96231b3b80d8