travis: don't run t_net.sh test

travis: don't run t_net.sh test

Not all travis instances are fit for running t_net.sh test due to
various configurations knob that we have no access to.

Prevent failures by not running t_net.sh on travis at all.
The t_net.sh is executed by other test rigs which we have more control
over.

The test is skipped by specifying RUN_SUDO=false which will make any
pre-test fail, forcing the Makefile to skip that particular test.

Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20200810161723.25576-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20684.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>