maintainer-feedback requested: [Bug 279743] devel/dbus: move session bus socket under XDG_RUNTIME_DIR

Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-desktop (Team)
<desktop@FreeBSD.org> for maintainer-feedback:
Bug 279743: devel/dbus: move session bus socket under XDG_RUNTIME_DIR
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=279743



--- Description ---
FreeBSD 14.1 added pam_xdg(8) to ensure XDG_RUNTIME_DIR is always defined.
Instead of littering /tmp with many randomly-named DBus sockets use
XDG_RUNTIME_DIR with non-random socket name. The directory is guaranteed to be
cleaned up on user logout or reside on tmpfs(5) thus cleaned up on reboot.
Also, better matches Linux with systemd.

DBus already uses XDG_RUNTIME_DIR to read service activation files from:

$ XDG_RUNTIME_DIR=$(mktemp -dt xdg-run) dbus-run-session sh
$ find /tmp/xdg-run.*
/tmp/xdg-run.mKuM3gZ7
/tmp/xdg-run.mKuM3gZ7/dbus-1
/tmp/xdg-run.mKuM3gZ7/dbus-1/services

Note, don't confuse with system bus aka dbus_enable=YES in /etc/rc.conf which
still uses /var/run/dbus/system_bus_socket.