When we're loading a framework header, first try to turn the framework

When we're loading a framework header, first try to turn the framework
into a module. This module can either be loaded from a module map in
the framework directory (which isn't quite working yet) or inferred
from an umbrella header (which does work, and replaces the existing
hack).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144877 91177308-0d34-0410-b5e6-96231b3b80d8