Add flag --enable-check-profile to clang-tidy.

Summary:
Add flag --enable-check-profile to clang-tidy.
It turns on per-matcher profiles in MatchFinder and prints a report to
stderr at the end.

Reviewers: alexfh

Subscribers: curdeius, cfe-commits

Differential Revision: http://reviews.llvm.org/D5937

llvm-svn: 220491