added atomic_dec32le0 for sem/mutex lock

mutex.c

@@ -13,8 +13,7 @@ int32_t mutex_lock(mutex_t* mutex) {
     //while(mutex->value <= 0);
     //mutex->value--;
     //return mutex->value;
-    while (atomic_dec32(&(mutex->value), (int32_t)0) <= 0);
-    return atomic_dec32(&(mutex->value), (int32_t)1);
+    return atomic_dec32le0(&(mutex->value), (int32_t)1);
 }
 
 int32_t mutex_unlock(mutex_t* mutex) {