Re-enable PTH testing for Cocoa.h and Carbon.h (and include testing for Objective-C++).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61965 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/SemaObjC/cocoa.m b/test/SemaObjC/cocoa.m
index 7cb1b52..ac7d1dc 100644
--- a/test/SemaObjC/cocoa.m
+++ b/test/SemaObjC/cocoa.m
@@ -1,4 +1,5 @@
-// RUN: clang %s -print-stats
+// RUN: clang %s -print-stats &&
+// RUN: clang -x objective-c-header -o %t %s && clang -token-cache %t %s
 #ifdef __APPLE__
 #include <Cocoa/Cocoa.h>
 #endif