Eliminate the comma locations from all of the Sema routines that deal

Eliminate the comma locations from all of the Sema routines that deal
with comma-separated lists. We never actually used the comma
locations, nor did we store them in the AST, but we did manage to
waste time during template instantiation to produce fake locations.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@113495 91177308-0d34-0410-b5e6-96231b3b80d8