Fix crash when disconnecting output
Fix crash when disconnecting output

If the output being disconnected contains views, and the views are being
relocated to another output of a different size, a transaction must
occur to reconfigure them. This means by the time
container_discover_outputs is called, the output is already disabled and
wlr_output is NULL.

I considered making it check output->wlr_output, but output->enabled
should work just as well and is more descriptive.

ascent12/sway,1ace/sway,SirCmpwn/sway,1ace/sway,ascent12/sway,1ace/sway,ascent12/sway