build on OpenBSD : no -lrt, set _BSD_SOURCE
Index: meson.build
--- meson.build.orig
+++ meson.build
@@ -29,7 +29,7 @@ cc = meson.get_compiler('c')
 add_project_arguments(
 	[
 		'-D_XOPEN_SOURCE=700',
-		'-D__BSD_VISIBLE',
+		'-D_BSD_SOURCE',
 		'-D_NETBSD_SOURCE',
 		'-DSEATD_VERSION="@0@"'.format(meson.project_version()),
 		'-DSEATD_DEFAULTPATH="@0@"'.format(defaultpath),
@@ -159,8 +159,8 @@ if get_option('libseat-logind') != 'disabled'
 endif
 
 # needed for cross-compilation
-realtime = meson.get_compiler('c').find_library('rt')
-private_deps += realtime
+# realtime = meson.get_compiler('c').find_library('rt')
+# private_deps += realtime
 
 if with_builtin
 	libseat_c_args += '-DBUILTIN_ENABLED=1'
@@ -221,14 +221,14 @@ if with_server
 		[ server_files, 'seatd/seatd.c' ],
 		include_directories: [include_directories('.', 'include')],
 		install: true,
-		dependencies: [realtime],
+#		dependencies: [realtime],
 	)
 	executable(
 		'seatd-launch',
 		[ 'seatd-launch/seatd-launch.c' ],
 		include_directories: [include_directories('.', 'include')],
 		install: true,
-		dependencies: [realtime],
+#		dependencies: [realtime],
 	)
 endif
 
