avcodec: hw accel with frame multithreading works since libavcodec 55.01.00

This is mostly useful if the hw accelerator cannot handle the stream.
The software decoder fallback will then use frame multithreading if it
supports it.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit b72986e83bad854b2db4a0e7e1d4e54be5140179)
Signed-off-by: Jean-Paul Saman <jpsaman@videolan.org>

modules/codec/avcodec/video.c

@@ -365,7 +365,7 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
          i_codec_id == CODEC_ID_H264 ||
          i_codec_id == CODEC_ID_VC1 || i_codec_id == CODEC_ID_WMV3) )
     {
-#ifdef HAVE_AVCODEC_MT
+#if defined(HAVE_AVCODEC_MT) && LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55, 1, 0)
         if( p_sys->p_context->thread_type & FF_THREAD_FRAME )
         {
             msg_Warn( p_dec, "threaded frame decoding is not compatible with ffmpeg-hw, disabled" );