When the target has no entries at all, it doesn't know how to merge.

This is a veeeeeeeeeeeery old bug, amplified by the fact that we do
weekly updates.  Fix by using the shiny new sample file plist code.

While there, make install provide output as well and
mop up a few minor issues with the previous code.

/var/run was cleared out before, but we'd rather not keep it
this way...  It is for pid files, nothing else.  Move the
terrible firmware dirty markers to /tmp instead.  Eventually,
we need a better way to keep track of subsystem state.  Cluttering
multiple files all over the disk is not a good solution.

While there, move the IPv4 sibling and add a require for the remaining
outside caller.

Remove the size settings for those mount points as a preparation,
because tmpfs does not need an upper bound.  Hardcode everything
now, replace mfs with tmpfs in an upcoming commit.

The default is to reboot anyway.  For everybody importing a backup
that has interface mismatches this means the backup did not come
from the same system, so it must be adapted on the console instead.

Caused by:	Omitted /var/run boot up purge

Only a workaround.  Need to take this to FreeBSD.