build: declare separate dependency for compositor.h

These are not specific to the launchers but to compositor.h, so name them that
way.

Once we can rely on the mentioned Meson PR, we can simplify this further.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

libweston/meson.build

@@ -92,6 +92,19 @@ dep_libweston = declare_dependency(
 	dependencies: deps_libweston
 )
 
+# XXX: We should be able to use dep_libweston.partial_dependency() instead
+# of this, but a Meson bug makes it not work. It will be fixed with
+# https://github.com/mesonbuild/meson/pull/5167
+# in hopefully Meson 0.51.
+dep_libweston_h = declare_dependency(
+	include_directories: include_directories('.'),
+	dependencies: [
+		dep_pixman.partial_dependency(compile_args: true),
+		dep_xkbcommon.partial_dependency(compile_args: true),
+		dep_wayland_server.partial_dependency(compile_args: true)
+	]
+)
+
 pkgconfig.generate(
 	lib_weston,
 	filebase: 'libweston-@0@'.format(libweston_major),
@@ -119,14 +132,7 @@ srcs_session_helper = [
 	'launcher-util.c',
 	'launcher-weston-launch.c',
 ]
-deps_session_helper = [
-	# for compositor.h needing pixman.h
-	dep_pixman.partial_dependency(compile_args: true),
-	# for compositor.h needing xkbcommon.h
-	dep_xkbcommon.partial_dependency(compile_args: true),
-	# for compositor.h needing wayland-server.h
-	dep_wayland_server.partial_dependency(compile_args: true)
-]
+deps_session_helper = [ dep_libweston_h ]
 
 if get_option('backend-drm')
 	deps_session_helper += dep_libdrm