Teach the search for modules to consider modules described by a module
map, so long as they have an umbrella header. This makes it possible
to introduce a module map + umbrella header for a given set of
headers, to turn it into a module.

There are two major deficiencies here: first, we don't go hunting for
module map files when we just see a module import (so we won't know
about the modules described therein). Second, we don't yet have a way
to build modules that don't have umbrella headers, or have incomplete
umbrella headers.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144424 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Modules/normal-module-map.cpp b/test/Modules/normal-module-map.cpp
index b6f584d..aeb569b 100644
--- a/test/Modules/normal-module-map.cpp
+++ b/test/Modules/normal-module-map.cpp
@@ -3,6 +3,12 @@
 
 // FIXME: The expected error here is temporary, since we don't yet have the
 // logic to build a module from a module map.
+#include "Umbrella/Umbrella.h"
+
+int getUmbrella() { 
+  return umbrella; 
+}
+
 #include "a1.h" // expected-error{{module 'libA' not found}}
 #include "b1.h"
 #include "nested/nested2.h"