util.sqlite3: Clean up unused variables
Many leftovers from the earlier version of util.sql this was based on
and cleanup applied there since then.
For full information on our dependencies, version requirements, and
where to find them, see https://prosody.im/doc/depends
If you have luarocks available on your platform, install the following:
- luaexpat
- luasocket
- luafilesystem
- luasec