Bug#983408: How to build the packages from sources

[Benoît Sibaud]

Hi,

well that may not be the right/proper way to produce the packages, but in the mean time, some instructions if you ever want to produce your own packages https://linuxfr.org/users/oumph/journaux/compilation-de-0-a-d-alpha-24-pour-debian-buster (in French).

Main changes I've noted:
- libmozjs78 instead of libmozjs38 (part of the 0.A.D. release notes)
- require nvtt >= 2.1.0 (only in Debian experimental for now), so I fallback to the non-system version (so extra libs to deploy, and maybe extra packages needed to build)

Regards,

-- 
Benoît Sibaud