[libclang] Add test case for r178374.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178378 91177308-0d34-0410-b5e6-96231b3b80d8

test/Index/modules-objc-categories.m

@@ -0,0 +1,10 @@
+@import category_top;
+@import category_left;
+
+@interface Sub : Foo
+- (void)left_sub;
+@end
+
+// RUN: rm -rf %t
+// RUN: c-index-test -test-load-source local -fmodules -fmodules-cache-path=%t %s -I%S/../Modules/Inputs | FileCheck %s
+// CHECK: modules-objc-categories.m:5:9: ObjCInstanceMethodDecl=left_sub:5:9 [Overrides @2:9]