Remove unused check from test.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176422 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/c11atomics.c

@@ -22,8 +22,6 @@ _Atomic(char*) p;
 _Atomic(float) f;
 _Atomic(vector) v;
 
-// CHECK-NOT: cmpxchg
-
 // CHECK: testinc
 void testinc(void)
 {