Re-introduce MatchFinder::addDynamicMatcher.

Differential Revision: http://llvm-reviews.chandlerc.com/D2114

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194222 91177308-0d34-0410-b5e6-96231b3b80d8
Introduce MatchFinder::matchAST.

Differential Revision: http://llvm-reviews.chandlerc.com/D2115

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194223 91177308-0d34-0410-b5e6-96231b3b80d8