lavc: Consistently prefix input buffer defines

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavcodec/ffv1enc.c

@@ -940,7 +940,7 @@ static int ffv1_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 
     if ((ret = ff_alloc_packet(pkt, avctx->width * avctx->height *
                              ((8 * 2 + 1 + 1) * 4) / 8 +
-                             FF_MIN_BUFFER_SIZE)) < 0) {
+                             AV_INPUT_BUFFER_MIN_SIZE)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n");
         return ret;
     }