When getattr requests the STX_CHANGE_COOKIE, request the full gamut of
caps (similarly to how ctime is handled). When the change attribute
seems to be valid, return it in the change_cookie field and set the flag
in the reply mask. Also, unconditionally enable
STATX_ATTR_CHANGE_MONOTONIC.
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>