libweston: make refresh rate configurable
Currently x11, wayland, and headless backends have their refresh rates hardcoded to 60000. It would be great if it's configurable by adding to weston_windowed_output_api
Currently x11, wayland, and headless backends have their refresh rates hardcoded to 60000. It would be great if it's configurable by adding to weston_windowed_output_api