Distinguish templates properly:

two templates with the same name are different if they have a different template parameter kind.
Fixes modules for cout << "ABC" << endl; mistakingly calling std::op<<(ostream,void*)

Also refresh the lookup for a decl context if it has external visible storage.


git-svn-id: http://root.cern.ch/svn/root/trunk@48263 27541ba8-7e3a-0410-8455-c3a389f83636