Support all null pointer literals in format strings.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150276 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/SemaCXX/format-strings-0x.cpp b/test/SemaCXX/format-strings-0x.cpp
index 9359c7b..e7c5904 100644
--- a/test/SemaCXX/format-strings-0x.cpp
+++ b/test/SemaCXX/format-strings-0x.cpp
@@ -10,4 +10,6 @@
 
   printf("%a", 1.0);
   scanf("%afoobar", fp);
+  printf(nullptr);
+  printf(*sp); // expected-warning {{not a string literal}}
 }