baseaudiosink: Resync when ringbuffer resets

When the ringbuffer gets restarted (like in setcaps), we *will* have
to resync against the new values.

Without this we end up blindly assuming the new samples align to the
old ones.

Conflicts:
	gst-libs/gst/audio/gstbaseaudiosink.c
Merge pull request #1 from adenexter/jb17654

baseaudiosink: Resync when ringbuffer resets