Use correct length modifier for size comparison in printf expression, fixes:

libavcodec/wmavoice.c:1906: warning: format `%lu' expects type `long unsigned int', but argument 5 has type `unsigned int'
approved by Ronald and Mans on IRC

Originally committed as revision 24218 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/wmavoice.c

@@ -1902,7 +1902,7 @@ static int wmavoice_decode_packet(AVCodecContext *ctx, void *data,
 
     if (*data_size < 480 * sizeof(float)) {
         av_log(ctx, AV_LOG_ERROR,
-               "Output buffer too small (%d given - %lu needed)\n",
+               "Output buffer too small (%d given - %zu needed)\n",
                *data_size, 480 * sizeof(float));
         return -1;
     }