Implicitly assume that a ObjC category to an unavailable interface is also unavailable;
only give an 'unavailable' error on the @implementation of the category. rdar://10234078

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141335 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed