Comment parsing: allow "\param ..." to describe variadic arguments

Original patch by Fariborz Jahanian; extended by me.

Fixes rdar://14124644


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184688 91177308-0d34-0410-b5e6-96231b3b80d8
Slightly improve cross-module merging for function templates.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184689 91177308-0d34-0410-b5e6-96231b3b80d8