The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
Using asciidoc-full was unnecessary to build KnightOS-related packages
since only the a2x command matters. This change makes
cross-compilation far more noticeably faster. Closure size for each
package reduced from around 7 MB to 2 MB.