xwayland: Replace need_rotate boolean with simple check on xdg-output

The need_rotate variable is only used once anymore and had semantics which lead
to errors in the past. In particular when negated we are dealing with a double

The variable gets replaced with a simple check on the xdg-output directly.

Signed-off-by: Roman Gilg <subdiff@gmail.com>
4 jobs for xwl-output in 5 minutes and 53 seconds (queued for 2 seconds)