Fix test failure by making sure this file isn't identical to any other file
included in the same test. Clang gets confused about whether it's already built
a module for this file, when running on a content-addressible filesystem.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174694 91177308-0d34-0410-b5e6-96231b3b80d8