Add test case that was causing an infinite loop when reading PCH files. The test works with ToT Clang already

llvm-svn: 108318
diff --git a/clang/test/Index/c-index-api-loadTU-test.m b/clang/test/Index/c-index-api-loadTU-test.m
index 22875db..4e5eed4 100644
--- a/clang/test/Index/c-index-api-loadTU-test.m
+++ b/clang/test/Index/c-index-api-loadTU-test.m
@@ -66,6 +66,10 @@
 - (IBAction) actionMethod:(id)arg;
 @end
 
+typedef struct X0 X1;
+struct X0;
+struct X0  {};
+
 // CHECK: c-index-api-loadTU-test.m:4:12: ObjCInterfaceDecl=Foo:4:12 Extent=[4:1 - 12:5]
 // CHECK: c-index-api-loadTU-test.m:6:32: ObjCIvarDecl=myoutlet:6:32 (Definition) Extent=[6:32 - 6:40]
 // CHECK: <invalid loc>:0:0: attribute(iboutlet)=