A lot of integration tests rely on the fact that there is a
window decoration.
The `KWIN_BUILD_DECORATIONS` pretty much only disables
build of Aurorae window decoration plug-in but otherwise
has no impact on KWin's core code base in terms of ifdefs
or dependencies required.
Re-enable building decorations to unbreak those tests.
Signed-off-by: Victoria Fischer <victoria.fischer@mbition.io>
Ensures KWin is also built with features disabled to catch when code is
added that requires a build-time guard
Signed-off-by: Eike Hein <eike.hein@mbition.io>