Function gio_sys::g_loadable_icon_load

pub unsafe extern fn g_loadable_icon_load(icon: *mut GLoadableIcon,
                                          size: c_int,
                                          type_: *mut *mut c_char,
                                          cancellable: *mut GCancellable,
                                          error: *mut *mut GError)
                                          -> *mut GInputStream