add buffyboard systemd service

this is an optional feature. systemd distributions wishing to deploy
buffyboard may add `WantedBy=default.target` to the Install section.

buffyboard/meson.build

@@ -24,20 +24,13 @@ executable('buffyboard',
 
 install_data('buffyboard.conf', install_dir: get_option('sysconfdir'))
 
-systemd = dependency('systemd', required: get_option('systemd-buffyboard-service'))
-if systemd.found()
-    system_unit_dir = systemd.get_variable(
-        pkgconfig: 'systemd_system_unit_dir',
-        pkgconfig_define: ['prefix', get_option('prefix')],
-    )
 
-    configure_file(
-      input : 'buffyboard.service.in',
-      output : 'buffyboard.service',
-      install : true,
-      install_dir : system_unit_dir,
-      configuration : {
-        'bindir' : get_option('prefix') / get_option('bindir'),
-      },
-    )
-endif
+configure_file(
+  input : 'buffyboard.service.in',
+  output : 'buffyboard.service',
+  install : true,
+  install_dir : get_option('libdir') / 'systemd/system',
+  configuration : {
+    'bindir' : get_option('prefix') / get_option('bindir'),
+  },
+)

meson_options.txt

@@ -1,3 +1,2 @@
 option('with-drm', type: 'feature', value: 'auto', description: 'Enable DRM backend')
 option('man', type: 'boolean', value: true, description: 'Install manual pages')
-option('systemd-buffyboard-service', type: 'feature', value: 'auto', description: 'Install systemd service file for buffyboard')