build: stop checking for logind

wlroots has removed its logind session backend [1]. It now relies
on libseat only.

[1]: https://github.com/swaywm/wlroots/pull/2786

meson.build

@@ -76,8 +76,6 @@ endif
 
 wlroots_features = {
 	'xwayland': false,
-	'systemd': false,
-	'elogind': false,
 	'libseat': false,
 }
 foreach name, _ : wlroots_features
@@ -318,7 +316,7 @@ summary({
 	'man-pages': scdoc.found(),
 }, bool_yn: true)
 
-if not wlroots_features['systemd'] and not wlroots_features['elogind'] and not wlroots_features['libseat']
+if not wlroots_features['libseat']
 	warning('The sway binary must be setuid when compiled without (e)logind or libseat')
 	warning('You must do this manually post-install: chmod a+s /path/to/sway')
 endif