When inferring a module for a framework, first determine whether that

framework is actually a subframework within a top-level framework. If
so, only infer a module for the top-level framework and then dig out
the appropriate submodule.

This helps us cope with an amusing subframeworks anti-pattern, where
one uses -F <framework>/Frameworks to get direct include access to the
subframeworks of a framework (which otherwise would not be
permitted).

llvm-svn: 148148