When suggesting a module import for a #include or #import, suggest the

When suggesting a module import for a #include or #import, suggest the
most specific (sub)module based on the actual file we find, rather
than always importing the top-level module. This means
that #include'ing <Foo/Blah.h> should give us the submodule Foo.Blah.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145942 91177308-0d34-0410-b5e6-96231b3b80d8