ipaddress: do not add IFA_FLAGS when not necessary

commit 37c9b94ed21d5779acc23d89a4 (add support for extended ifa_flags)
introduced a regression:

        # ./ip/ip addr add dev eth0
        RTNETLINK answers: Invalid argument

This is due to old kernels don't support IFA_FLAGS flag, we should not
use it if we don't use the flags beyond old .ifa_flags.

Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
1 file changed