Fix AMR block length for no data mode when muxing mov.

Fixes ticket #550.
This had been analyzed and reported by Igor Levin, igor d levin comverse com

libavformat/movenc.c

@@ -2013,7 +2013,7 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
     if (enc->codec_id == CODEC_ID_AMR_NB) {
         /* We must find out how many AMR blocks there are in one packet */
         static uint16_t packed_size[16] =
-            {13, 14, 16, 18, 20, 21, 27, 32, 6, 0, 0, 0, 0, 0, 0, 0};
+            {13, 14, 16, 18, 20, 21, 27, 32, 6, 0, 0, 0, 0, 0, 0, 1};
         int len = 0;
 
         while (len < size && samplesInChunk < 100) {