build: drop xwayland option

This is unnecessary because Xwayland logic doesn't bring in new
dependencies. We can just compile in our Xwayland-related code
when wlroots has been built with Xwayland support.

See this Sway patch: swaywm/sway#8165

README.md

@@ -34,11 +34,9 @@ $ ninja -C build
 By default, this builds a debug build. To build a release build, use `meson
 build --buildtype=release`.
 
-Cage comes with compile-time support for XWayland. To enable this,
-first make sure that your version of wlroots is compiled with this
-option. Then, add `-Dxwayland=true` to the `meson` command above. Note
-that you'll need to have the XWayland binary installed on your system
-for this to work.
+Cage comes with compile-time support for XWayland. To enable this, make sure
+that your version of wlroots is compiled with this option. Note that you'll
+need to have the XWayland binary installed on your system for this to work.
 
 You can run Cage by running `./build/cage APPLICATION`. If you run it from
 within an existing X11 or Wayland session, it will open in a virtual output as

meson.build

@@ -64,15 +64,7 @@ server_protos = declare_dependency(
   sources: server_protos_headers,
 )
 
-if not get_option('xwayland').disabled()
-  wlroots_has_xwayland = wlroots.get_variable(pkgconfig: 'have_xwayland', internal: 'have_xwayland') == 'true'
-  if get_option('xwayland').enabled() and not wlroots_has_xwayland
-    error('Cannot build Cage with XWayland support: wlroots has been built without it')
-  endif
-  have_xwayland = true
-else
-  have_xwayland = false
-endif
+have_xwayland = wlroots.get_variable(pkgconfig: 'have_xwayland', internal: 'have_xwayland') == 'true'
 
 version = '@0@'.format(meson.project_version())
 git = find_program('git', native: true, required: false)

meson_options.txt

@@ -1,2 +1 @@
 option('man-pages', type: 'feature', value: 'auto', description: 'Generate and install man pages')
-option('xwayland', type: 'feature', value: 'auto', description: 'Enable support for X11 applications')