Runtime check of poisoning derived class members.

Summary: Simple test case to verify that an instance of a derived class with virtual base is properly poisoned

Reviewers: eugenis, kcc

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D11733

modified test to be more concise, and check the local pointer to the destroyed object

revised test to not examine padding- only explicit object members

llvm-svn: 243913