Tweak the storage mechanism for a set of overloaded template names in

the TemplateName class. Nothing actually changes, but I find this less
objectionable (and it will factor into an upcoming change).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@123508 91177308-0d34-0410-b5e6-96231b3b80d8