/*
* Get the default X11 Colormap on the specified Display and screen.
* Raises a RunTimeError exception if the colormap could not be
* allocated.
*
* Note: This method is not available unless Imlib2-Ruby was compiled
* with X11 support. You can check the constant Imlib2::X11_SUPPORT to
* see if X11 support is available.
*
* Examples:
* cmap = Imlib2::X11::Colormap.new display, screen_num
*
*/
VALUE cmap_new(VALUE klass, VALUE display, VALUE screen) {