Fix linking issue (missing wayland-client library)

Linking libflutter_linux_gtk.so shared library fails on
embedded platform as follows:

 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_destroy'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_marshal'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_destroy'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_marshal'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_destroy'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_marshal'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_destroy'
 fl_renderer_wayland_dispose(_GObject*):
	error: undefined reference to 'wl_proxy_marshal'
 fl_renderer_wayland_create_surfaces(_FlRenderer*, _GtkWidget*, void*, void*, void**, void**, _GError**):
	error: undefined reference to 'wl_proxy_marshal_constructor'
 fl_renderer_wayland_create_surfaces(_FlRenderer*, _GtkWidget*, void*, void*, void**, void**, _GError**):
	error: undefined reference to 'wl_proxy_marshal_constructor'
 fl_renderer_wayland_create_surfaces(_FlRenderer*, _GtkWidget*, void*, void*, void**, void**, _GError**):
	error: undefined reference to 'wl_surface_interface'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_proxy_marshal_constructor'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_proxy_add_listener'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_display_roundtrip'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_proxy_marshal_constructor'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_registry_interface'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_subsurface_interface'
 fl_renderer_wayland_on_window_map(_FlRendererWayland*, _GtkWidget*):
	error: undefined reference to 'wl_region_interface'
 registry_handle_global(void*, wl_registry*, unsigned int, char const*, unsigned int):
	error: undefined reference to 'wl_proxy_marshal_constructor_versioned'
 registry_handle_global(void*, wl_registry*, unsigned int, char const*, unsigned int):
	error: undefined reference to 'wl_subcompositor_interface'

As fl_renderer_wayland.cc uses directly some of the wayland-client
related functions it should also add this library as a dependency.

Signed-off-by: Damian Wrobel <dwrobel@ertelnet.rybnik.pl>

Author: dwrobel

shell/platform/linux/config/BUILD.gn

@@ -12,7 +12,10 @@ if (build_glfw_shell) {
 }
 
 pkg_config("gtk") {
-  packages = [ "gtk+-3.0" ]
+  packages = [
+    "gtk+-3.0",
+    "wayland-client",
+  ]
 }
 
 pkg_config("egl") {