listener: ipv6only socket bind support

listener: ipv6only socket bind support

According to RFC3493 and most Linux distributions, default value is to
work in IPv4-mapped mode. If there is a requirement to bind same port
on same ip addresses but different handlers for both IPv4 and IPv6,
it is required to set IPV6_V6ONLY socket option to be sure that the
code works as expected without affected by bindv6only sysctl setting
in system.

See an example working with this patch:
https://gist.github.com/demirten/023008a63cd966e48b0ebcf9af7fc113

Closes: #640 (cherry-pick)
(cherry picked from commit 387d91f9ab95df8ac3d7bb58493310ad4a377dcf)