t_client.sh: conditionally skip ifconfig+route check

t_client.sh: conditionally skip ifconfig+route check

For --dev null or --dev-type af_unix:lwipopenvn tests, there will be
no visible change to ifconfig or route output, so tests will fail
("how can this be?").  Set EXPECT_IFCONFIG4_<n>=- to skip this
check.

(Simply leaving both EXPECT_IFCONFIG* vars empty and using that as
trigger would interfere with the magic from commit df0b00c25)

v2: fix string-equal comparison

Change-Id: Iec1953415afb53755488dd44407568e72d28e854
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20240928200508.23747-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29473.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>