build: use WLR_HAS_* to decide whether suid is required
build: use WLR_HAS_* to decide whether suid is required

Maybe systemd/elogind is found but wlroots was built without them. Print
the warning message depending on the WLR_HAS_* defines instead.

While at it, don't print the message if wlroots has been build with
libseat.

1ace/sway,1ace/sway,1ace/sway