Function glib_sys::g_date_time_add_full

pub unsafe extern "C" fn g_date_time_add_full(
    datetime: *mut GDateTime, 
    years: c_int, 
    months: c_int, 
    days: c_int, 
    hours: c_int, 
    minutes: c_int, 
    seconds: c_double
) -> *mut GDateTime