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
negation.

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 4 minutes and 45 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Docker Image
passed #4351714
debian-testing

00:00:23

 
  Build And Test
passed #4351715
autotools

00:04:21

passed #4351717
meson

00:00:54

passed #4351719
meson-noglamor

00:00:53