Change VariadicOperatorMatcherInterface<> to take an ArrayRef<DynTypedMatcher>.

Summary:
Change VariadicOperatorMatcherInterface<> to take an ArrayRef<DynTypedMatcher>.
This simplifies its implementation and use.
Also reduces the number of symbols in Registry.cpp.o, which we are always in need.

Reviewers: klimek

CC: cfe-commits, revane, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2216

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195127 91177308-0d34-0410-b5e6-96231b3b80d8