Add a negative test case

Author: luciechoi

llvm/test/CodeGen/SPIRV/extensions/SPV_KHR_maximal_reconvergence/enable-maximal-reconvergence.ll

@@ -9,4 +9,12 @@ entry:
   ret void
 }
 
-attributes #0 = { mustprogress nofree noinline norecurse nosync nounwind willreturn memory(none) "enable-maximal-reconvergence"="true" "frame-pointer"="all" "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+; CHECK-NOT: OpExtension "SPV_KHR_maximal_reconvergence"
+; CHECK-NOT: OpExecutionMode {{.*}} MaximallyReconvergesKHR
+define void @negative() local_unnamed_addr #1 {
+entry:
+  ret void
+}
+
+attributes #0 = { "enable-maximal-reconvergence"="true" "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }
+attributes #1 = { "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }