Add TypeLoc traversal to the RecursiveASTVisitor! Because the TypeLocs don't

Add TypeLoc traversal to the RecursiveASTVisitor! Because the TypeLocs don't
contain all the same information that their Types do, we will fall back to
traversing the Types instead. The default TypeLoc visitor calls the matching
Type visitor so that existing clients should continue to work with no change.

Also adds element traversal to the ExtVectorType.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107592 91177308-0d34-0410-b5e6-96231b3b80d8