roothack: work around build problem on head (10-CURRENT)

It seems that libarchive interface has changed.
Ultimately I would like replace roothack with init(8) chroot configuration
(init_script + init_chroot).
hc-install: remove install.log just before reboot

Just in case /tmp is a persistent directory and  the log file contains
any sensitive information.  Typically /tmp is ephemeral though.
hc-install: don't quit/restart installer after issuing shutdown command
hc-install: abort upon zfsinstall failure
make installworld and installkernel quieter

To do: suggest this change upstream.
force usage of HybridCluster branded loader menu

orbbw was hijacked in hc source tree to be a hybrid cluster logo.
For 9.2 the upstream has changed a default logo to a tribute one that is
branded with Nakatomi BSD 9.2 theme as can be seen in Die Hard movie.
So now we have to explicit about which logo we actually.

Long term, it's better to restore orbbw to its original look and re-add
the hc logo as a new log and then the default to it.

logo
hc-install: use new, stable naming for a system image included with the iso