Fix PR10177 where non-type template arguments to alias templates are not marked as used in dependent contexts. The fix actually forces non-dependent names to be checked at template definition time as expected from the standard.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@214192 91177308-0d34-0410-b5e6-96231b3b80d8