Teach global selector lookup to ignore hidden methods, which occur
when the methods are declared in a submodule that has not yet been
imported. Part of <rdar://problem/10634711>. 


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172635 91177308-0d34-0410-b5e6-96231b3b80d8