Prior to adding the new "expected-no-diagnostics" directive to VerifyDiagnosticConsumer, make the necessary adjustment to 580 test-cases which will henceforth require this new directive.

llvm-svn: 166280
diff --git a/clang/test/Sema/assign-null.c b/clang/test/Sema/assign-null.c
index 7f172b1..ac90850 100644
--- a/clang/test/Sema/assign-null.c
+++ b/clang/test/Sema/assign-null.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
+// expected-no-diagnostics
 
 #include <stddef.h>