Add -frtti and -fexceptions to tests that assume these are on.

Summary:
We now have targets that don't enable rtti/exceptions by default, and the
ASTMatchers tests are assuming that these features are on (e.g: They use
dynamic_cast or try).

Reviewers: klimek, thakis, djasper

Subscribers: klimek, cfe-commits

Differential Revision: http://reviews.llvm.org/D7892

llvm-svn: 230984