Add a triple to new test.

NULL is just 0 on Windows, so the Wsentinel part of the test doesn't pass there.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207607 91177308-0d34-0410-b5e6-96231b3b80d8

test/Headers/stddefneeds.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -Wsentinel -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -triple x86_64-apple-macosx10.9.0 -verify -Wsentinel -std=c++11 %s
 
 ptrdiff_t p0; // expected-error{{unknown}}
 size_t s0; // expected-error{{unknown}}