bitcoind prelim build

systemd service file 'bitcoind.service' is a tragic failure.

So tragic is systemd in fact, that I'm seriously considering switching to
Runit + Ignite. In this case, I will need to create a runit service file
for bitcoind, which this package should be able to install manually. I
assume a PR on ignite would be welcome, however.

However, I can't switch to Runit without at least experimenting on a VM.
Ideally I would completely replace systemd with Runit.

If Runit fails, the other option is apparently Monit or Mongroup + Mon.
Since this package closely relates to the electrum-server-git PKGBUILD,
I'd like to keep everything under one paradigm (Runit). IMO Runit is
one of the more promising init systems available today.
switch to private bitcoind PKGBUILD dep