distro packaging, makefiles, deps, systemd, new tools

[Jason A. Donenfeld]

Hey Christian, Daniel, Dan, and other maintainers,

The next snapshot is going to have some improvements to the tooling,
and along with this comes a more complicated Makefile. I wanted to run
the changes by y'all (downstreams).

- The makefile now has a few WITH_{FEATURE}=yes|no environment flags,
as well as auto-detection. Documentation is here:
https://git.zx2c4.com/WireGuard/plain/src/tools/INSTALL
And the Makefile itself is here:
https://git.zx2c4.com/WireGuard/tree/src/tools/Makefile

Question: does this propose a desirable situation for you as a downstream?


- The wg-config script is now called wg-quick and is quite simple and
nice. Documentation:
https://git.zx2c4.com/WireGuard/about/src/tools/wg-quick.8
And source:
https://git.zx2c4.com/WireGuard/tree/src/tools/wg-quick.bash

OpenWRT should _not_ ship this. NixOS probably should not ship this.
When systemd-networkd gets support for WireGuard, systemd-based
distros should not ship this. But everybody else who just wants a
simple rough script for quickly bringing up and down VPNs can ship
this, as it's a big help to users. It's installed according to the
documentation for the Makefile above.

- There's now an "upstream" systemd unit for wg-quick, called
wg-quick at .service. It's pretty simple:
https://git.zx2c4.com/WireGuard/tree/src/tools/wg-quick@.service

Question: does this unit seem sane to you? Can you ship it downstream
as is, or will you need modifications?

Thanks,
Jason