ffplay: add missing filt_in assignment after video filter reconfigure

Fixes segfaults on changing resolution.
Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -1693,6 +1693,7 @@ static int video_thread(void *arg)
                 av_free_packet(&pkt);
                 goto the_end;
             }
+            filt_in  = is->in_video_filter;
             filt_out = is->out_video_filter;
             last_w = is->video_st->codec->width;
             last_h = is->video_st->codec->height;