When trying to set up multiple derper instances meshing with each
other, it turned out that while one can specify an alternative
listening port using the -a flag, the TLS hostname gets incorrectly
determined and includes the set alternative listening port as part of
the hostname. Thus, the TLS hostname validation always fails when the
-mesh-with values have ports.
Updates #9949
Signed-off-by: Thomas Kosiewski <thomas.kosiewski@loft.sh>
b2ae8fdf80