Autoconf: Print the GNU C Library version when needed in autogen.sh

[tcpdump] / tests / ntp-time.out

    1  2017-08-23 13:21:56.928550 IP 132.199.152.129.49445 > 132.199.4.1.123: NTPv4, Client, length 48
    2  2017-08-23 13:21:56.928851 IP 132.199.4.1.123 > 132.199.152.129.49445: NTPv4, Server, length 48