any names that aren't in the appropriate identifier namespaces. Fixes
an embarrassing bug where we give a redefinition error due to an
Objective-C category (<rdar://problem/9388207>).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131036 91177308-0d34-0410-b5e6-96231b3b80d8
Douglas Gregor