CHECK-LABEL-ify some code gen tests to improve diagnostic experience when tests fail.

llvm-svn: 188447
diff --git a/clang/test/CodeGen/fast-math.c b/clang/test/CodeGen/fast-math.c
index 76cfbbd..4a51358 100644
--- a/clang/test/CodeGen/fast-math.c
+++ b/clang/test/CodeGen/fast-math.c
@@ -2,7 +2,7 @@
 float f0, f1, f2;
 
 void foo(void) {
-  // CHECK: define void @foo()
+  // CHECK-LABEL: define void @foo()
 
   // CHECK: fadd fast
   f0 = f1 + f2;