fcplay: Correct metadata.next_track sequence for gapless playback

fcplay: Correct metadata.next_track sequence for gapless playback

The kernel demands the metadata to be set before the next_track is
signaled (since 2013).
Calling next_track before set metadata will case the next_track to be
'lost' in core's snd_compr_next_track().

Reverse the call order of next_track and set_metadata to fix this.

Fixes: 40603c037c8d ("fcplay: Modify play_samples func to support gapless playback.")
Closes: https://github.com/alsa-project/tinycompress/pull/33
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>