Prevent generation of duplicate EXPECT_IFCONFIG entries

Prevent generation of duplicate EXPECT_IFCONFIG entries

Previously, if t_client.rc did not source t_client_ips.rc,
update_t_client_ips.sh would add (the same) EXPECT_IFCONFIG entries to
t_client_ips.rc on every run. This patch makes update_t_client_ips.sh
check if
the entry exists before trying to add it.

v2: prevent partial matches of the EXCEPT_IFCONFIG variable name

Signed-off-by: Samuli Seppänen <samuli@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1478613963-28077-1-git-send-email-samuli@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg12965.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>