[CFI] Disable CFI checks for __cxa_decrement_exception_refcount

Summary:
exception_header->exceptionDestructor is a void(*)(void*) function
pointer; however, it can point to destructors like std::
exception::~exception that don't match that type signature.

Reviewers: pcc, vitalybuka

Reviewed By: vitalybuka

Subscribers: kcc, christof, cfe-commits

Differential Revision: https://reviews.llvm.org/D45455

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@329629 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed