ffplay: fix a crash caused by aborting the video queue

If the video queue is aborted, we have to pop the pending ALLOC event or wait
for the allocation to complete, because the current code assumes that
VideoState->pictq_windex does not change until the allocation is complete.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffplay.c

@@ -1356,6 +1356,12 @@ static int queue_picture(VideoState *is, AVFrame *src_frame, double pts1, int64_
         while (!vp->allocated && !is->videoq.abort_request) {
             SDL_CondWait(is->pictq_cond, is->pictq_mutex);
         }
+        /* if the queue is aborted, we have to pop the pending ALLOC event or wait for the allocation to complete */
+        if (is->videoq.abort_request && SDL_PeepEvents(&event, 1, SDL_GETEVENT, SDL_EVENTMASK(FF_ALLOC_EVENT)) != 1) {
+            while (!vp->allocated) {
+                SDL_CondWait(is->pictq_cond, is->pictq_mutex);
+            }
+        }
         SDL_UnlockMutex(is->pictq_mutex);
 
         if (is->videoq.abort_request)