OpenSUSE inherits the hostname value from DHCP without updating its X11
authentication cookie, and it keeps the initial value in
`XAUTHLOCALHOSTNAME`.
To avoid breaking the X11 applications, OpenSUSE patches libxcb so that
it also considers the value in `XAUTHLOCALHOSTNAME` as another possible
hostname.
https://bugzilla.opensuse.org/show_bug.cgi?id=262309
To cope with that behavior we need to check `XAUTHLOCALHOSTNAME` too
and, if we have a cookie with that address, propagate it inside the
container adjusting its address to the canonical hostname
`unames.nodename`.
Fixes: #4043
Signed-off-by: Ludovico de Nittis <ludovico.denittis@collabora.com>