Tie the macOS tests in test/Integration to the latest macOS SDK

This change will ensure that these tests won't fail when a new SDK that
utilizes new compiler features is used.
See https://reviews.llvm.org/D32178 for more context.

llvm-svn: 304542
diff --git a/clang/test/Integration/cocoa.m b/clang/test/Integration/cocoa.m
index d814b3e..91d8682 100644
--- a/clang/test/Integration/cocoa.m
+++ b/clang/test/Integration/cocoa.m
@@ -1,4 +1,5 @@
 // RUN: %clang -arch x86_64 %s -fsyntax-only -Xclang -print-stats
+// REQUIRES: macos-sdk-10.12
 #ifdef __APPLE__
 #include <Cocoa/Cocoa.h>
 #endif