This reverts commit
adcf4c81c58511b67644e17fa743d1729d3c9ccf.
We have a better solution for the problem of making two processes run in
the same namespace, and --listener is not needed hence and should be
dropped.
Conflicts:
man/systemd-socket-proxyd.xml
<para>
<command>systemd-socket-proxyd</command> is a generic
socket-activated network socket forwarder proxy daemon
- for IPV4, IPv6 and UNIX stream sockets. It may be used
+ for IPv4, IPv6 and UNIX stream sockets. It may be used
to bi-directionally forward traffic from a local listening socket to a
local or remote destination socket.</para>