avfilter/vf_tiltandshift: Free dst on error

Fixes: CID1559901 Resource leak

Sponsored-by: Sovereign Tech Fund
Reviewed-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavfilter/vf_tiltandshift.c

@@ -237,8 +237,10 @@ static int output_frame(AVFilterLink *outlink)
 
     // set correct timestamps and props as long as there is proper input
     ret = av_frame_copy_props(dst, s->input);
-    if (ret < 0)
+    if (ret < 0) {
+        av_frame_free(&dst);
         return ret;
+    }
 
     // discard frame at the top of the list since it has been fully processed
     list_remove_head(s);