[TTC] Installer Enhancement -- dpv

NB: TTC subject-moniker can be either "Time To Commit" or "Threat To Commit"
;D (hoping to start a trend here)

Heads-up,

I'm getting itchy-fingers to commit the following:
https://reviews.freebsd.org/D714

Been sitting idle for 16 days, if it reaches 21 days with no outcry, I'm
pulling it in.

5 days to raise opposition (which I guarantee to receive collegially; no
worries).

NB: The patch was reviewed and approved once-before by julian; the only
thing that changed between prior approval/review was that I ripped
dpv/libdpv/libfigpar out into a separate commit and then rebased the changes
to bsdinstall into a [vastly] smaller differential review. So we're not
talking about pushing unreviewed code into the tree (just wanted to make
that clear) -- rather that it's just been sitting in the unreviewed state
because of the rebase.
-- 
Devin