avcodec/libxvid: Remove set-but-unused variable

Set-but-unused since 2101b99777.

Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/libxvid.c

@@ -685,7 +685,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
     if (x->quicktime_format) {
         AVFrame *picture;
         AVPacket *packet;
-        int size, got_packet, ret;
+        int size, got_packet;
 
         packet = av_packet_alloc();
         if (!packet)
@@ -716,7 +716,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
         picture->data[2] = picture->data[1] + size / 4;
         memset(picture->data[0], 0, size);
         memset(picture->data[1], 128, size / 2);
-        ret = xvid_encode_frame(avctx, packet, picture, &got_packet);
+        xvid_encode_frame(avctx, packet, picture, &got_packet);
         av_packet_free(&packet);
         av_free(picture->data[0]);
         av_frame_free(&picture);