[modules] If a submodule has re-definitions of the same macro, only the last definition will be used as the "exported" one.

Fixes rdar://13562262

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178622 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed