Reset rbsp buffer size when freeing its data buffer.

Patch by Mike Scheutzow $(name) AT alcatel 'minus' lucent com

Originally committed as revision 20531 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h264.c

@@ -1999,6 +1999,8 @@ static void free_tables(H264Context *h){
         av_freep(&hx->s.obmc_scratchpad);
         av_freep(&hx->rbsp_buffer[1]);
         av_freep(&hx->rbsp_buffer[0]);
+        hx->rbsp_buffer_size[0] = 0;
+        hx->rbsp_buffer_size[1] = 0;
         if (i) av_freep(&h->thread_context[i]);
     }
 }