Treat -Wformat=0 as an alias for -Wformat.

Fixes PR9195.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148300 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/format-strings-scanf.c b/test/Sema/format-strings-scanf.c
index 4d9843c..be70357 100644
--- a/test/Sema/format-strings-scanf.c
+++ b/test/Sema/format-strings-scanf.c
@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -triple i386-apple-darwin9 -Wformat-nonliteral %s
 
+// Test that -Wformat=0 works:
+// RUN: %clang_cc1 -fsyntax-only -Werror -Wformat=0 %s
+
 #include <stdarg.h>
 typedef __typeof(sizeof(int)) size_t;
 typedef struct _FILE FILE;