Coder fails to build [1] on FreeBSD:

transport_unix.go:52:10: cannot use t (variable of type *unixTransport) as type transport in return statement:
        *unixTransport does not implement transport (missing SendNullByte method)

Update godbus dependency to latest, post upstream PR #332 [2] via #237

Fixes: #4516

[1] #4516
[2] godbus/dbus#332
[3] godbus/dbus#237

coder currently wants GNU getopt for reasons:

  # BSD getopt (which is installed by default on Macs) is not supported.

Although getopt is notoriously non-portable and behaviour differs across
implementations and operating systems, in leui of a discussion
to remove this specific implementation requirement...

Add a GETOPT environment variable in lib.sh and build_go.sh to allow
specifying getopt location, leaving the current value 'getopt' as the
default.

Some operating systems and user environments may have or allow for
installation of multiple go versions. In the cases where these environments
are not isolated (jails, containers, etc), a `go` command, either by way of
symlink pointing to a desired go installation or default version, may not
exist, be installed, or may change targets over time.

As an example, FreeBSD Ports & Packages allows the concurrent installation
of multiple golang versions, with go commands being suffixed with a version
string (eg: go119).

In order to deterministiscally build packages on these systems, particularly
in the case of "official" packaging systems @ downstreams, it is necessary
to be able to explicitly specify what language versions is used, rather
than have them be autodetected, where PATH ordering can matter and interfere
or where the default binary name can change over time according to user
preference.

Accordingly, allow specifying `go` command location via a GOCMD environment
variable in build_go.sh.

See Also:

  golang/go#28043

I was in ports Makefile not bash mode.

`./scripts/build_go.sh --os freebsd` fails to build with the following
(unique) errors:

  termios/sgtty_unix.go:13:20: undefined: unix.TCGETS
  termios/termios.go:33:10: undefined: TTYIO
  termios/termios.go:39:9: undefined: MakeRaw
  termios/var_unix.go:42:38: undefined: syscall.IUTF8
  termios/var_unix.go:50:37: undefined: syscall.OFILL
  termios/var_unix.go:51:37: undefined: syscall.OFDEL

This was resolved upstream in u-root/u-root/pull/2544 [1]
via tailscale/tailscale/pull/6155 [2] in u-root/u-root/commit/18fd0ce36 [3]

Update termios (u-root) dependency to a commit just past that
change.

[1] u-root/u-root#2544
[2] tailscale/tailscale#6155
[3] u-root/u-root@18fd0ce36

Fixes: #4516

`./scripts/build_go.sh --os freebsd` fails to build with the following
(unique) errors:

  cli/schedule.go:223:19: undefined: tz.TimezoneIANA
  cli/util.go:116:17: undefined: tz.TimezoneIANA

coderd/util/tz currently contains per-OS implementions (one file per supported
OS), but is missing a tz_freebsd.go.

Follow the existing pattern by creating a tz_freebsd.go from tz_linux.go.

FreeBSD supports standard IANA zoneinfo (and /etc/localtime), so no other
changes are required.

Fixes: #4516