Ignore stack-buffer-overflow in std::_Find_elem<*> / std::num_get<...>::_Getifld

Reviewed at http://reviews.llvm.org/D3650

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208215 91177308-0d34-0410-b5e6-96231b3b80d8