Function allegro_color_sys::allegro_color::al_color_rgb_to_cmyk

pub unsafe extern "C" fn al_color_rgb_to_cmyk(
    red: c_float,
    green: c_float,
    blue: c_float,
    cyan: *mut c_float,
    magenta: *mut c_float,
    yellow: *mut c_float,
    key: *mut c_float
)