wayland: generalize wayland-protocols code generation

Make it easy to add a new protocol to the list without duplicating
logic.

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22682>

meson.build

@@ -1913,10 +1913,6 @@ if with_platform_wayland
     dep_wayland_egl = dependency('wayland-egl-backend', version : '>= 3')
     dep_wayland_egl_headers = dep_wayland_egl.partial_dependency(compile_args : true)
   endif
-  wayland_dmabuf_xml = join_paths(
-    dep_wl_protocols.get_variable(pkgconfig : 'pkgdatadir'), 'unstable',
-    'linux-dmabuf', 'linux-dmabuf-unstable-v1.xml'
-  )
   pre_args += '-DWL_HIDE_DEPRECATED'
 endif