Add dependencies to enable Wayland

Unfortunately, FLTK's cmake build system does not appear to have an option to force wayland no matter what and fail building if wayland dependencies are not present (there's FLTK_BACKEND_WAYLAND and FLTK_USE_WAYLAND, but both are overridden by auto-detection in the CMake files). We can only provide dependencies and hope that FLTK picks up wayland correctly.