Oops, I broke pause/resuming from a statefile r4514
Everything should be fixed out.

Also we now avoid opening the audio device until we have a
playable audio_format set.  This is a long-standing bug that got
exposed more blatantly with the single array.

Thanks to MattD in #mpd for reporting my breakage.

git-svn-id: https://svn.musicpd.org/mpd/trunk@4516 09075e82-0dd4-0310-85a5-a0d7c8717e4f