look for an init system and auto install based on what is found

contrib/openrc/meson.build

@@ -1,5 +1,3 @@
-openrc = get_option('openrc')
-
 openrc_config_data = configuration_data()
 openrc_config_data.set('SBINDIR', join_paths(get_option('prefix'), get_option('sbindir')))
 openrc_config_data.set('LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir'), meson.project_name()))
@@ -10,7 +8,9 @@ openrc_config_data_file = configure_file(
     configuration: openrc_config_data
 )
 
-if openrc
+openrc = find_program ('openrc', required: false)
+
+if openrc.found()
     install_data(
         openrc_config_data_file,
         install_dir: join_paths(get_option('sysconfdir'), 'init.d')