watch_arg: greater_flag -> above_threshold

testcase/hptest.c

@@ -37,7 +37,7 @@ int main() {
         .length_byte = sizeof(int),
         .threshold = 20,
         .unsigned_flag = 0,
-        .greater_flag = 1,
+        .above_threshold = 1,
         .time_ns = 2000, // on hyper-v, 1us will block all system. 2us just fine, maybe 1us is too short for hyper-v
     };
     start_watch(w_arg);