lavc/pthread_frame: protect read state access in setup finish function

libavcodec/pthread_frame.c

@@ -509,11 +509,11 @@ void ff_thread_finish_setup(AVCodecContext *avctx) {
 
     if (!(avctx->active_thread_type&FF_THREAD_FRAME)) return;
 
+    pthread_mutex_lock(&p->progress_mutex);
     if(p->state == STATE_SETUP_FINISHED){
         av_log(avctx, AV_LOG_WARNING, "Multiple ff_thread_finish_setup() calls\n");
     }
 
-    pthread_mutex_lock(&p->progress_mutex);
     p->state = STATE_SETUP_FINISHED;
     pthread_cond_broadcast(&p->progress_cond);
     pthread_mutex_unlock(&p->progress_mutex);