vf_fps: add final flushed frames to the dropped frame count

libavfilter/vf_fps.c

@@ -104,6 +104,7 @@ static av_cold void uninit(AVFilterContext *ctx)
 {
     FPSContext *s = ctx->priv;
     if (s->fifo) {
+        s->drop += av_fifo_size(s->fifo) / sizeof(AVFilterBufferRef*);
         flush_fifo(s->fifo);
         av_fifo_free(s->fifo);
     }