Fix order of evaluation bug in DynTypedMatcher::constructVariadic().

Fix order of evaluation bug in DynTypedMatcher::constructVariadic().
If it evaluates right-to-left, the vector gets moved before we read the
kind from it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219624 91177308-0d34-0410-b5e6-96231b3b80d8