tests/pthread_condition_variable: small improvements

tests/pthread_condition_variable/main.c

@@ -52,6 +52,7 @@ static void *second_thread(void *arg)
 
 int main(void)
 {
+    puts("START");
     count = 0;
     is_finished = 0;
     expected_value = 1000ul * 1000ul;
@@ -74,10 +75,14 @@ int main(void)
             puts("condition fulfilled.");
             is_finished = 1;
             mutex_unlock(&mutex);
-            return 0;
+            break;
         }
 
         pthread_cond_wait(&cv, &mutex);
         mutex_unlock(&mutex);
     }
+
+    puts("SUCCESS");
+
+    return 0;
 }