Parsing and semantic analysis for template-ids that name overloaded

Parsing and semantic analysis for template-ids that name overloaded
operators, e.g.,

  operator+<int>

which now works in declarators, id-expressions, and member access
expressions. This commit only implements the non-dependent case, where
we can resolve the template-id to an actual declaration.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@85966 91177308-0d34-0410-b5e6-96231b3b80d8