[StevenMaude]

Something must have changed between the old version of Alpine used and
the current, as changed in a2d0975.

The Docker-based build (make build) went from:

(previously)

https-redirect: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/l, with debug_info, not stripped

to

(now)

https-redirect: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib/ld-, not stripped

This binary doesn't run under Ubuntu 18.04 LTS as it can't find the
interpreter.

Instead, build a static binary to avoid this entirely. This is in line
with how hookbot and hanoverd are built.

With this commit and make build

https-redirect: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, not stripped