When adding a new database when reloading the config at runtime the
architecture must be passed when creating the database. Otherwise we end up
with the new database sharing the internal storage with the x86_64 database
which leads to very confusing behavior.
* Do HTTP head request first when loading database from mirror to avoid
downloading the full database all the time
* Use the last modification date of the local database file because with
the persistent storage even local database reloads became a bit expensive
Simply adding `--sign` to the `makepkg` flags doesn't work because it would
require setting up GPG within the chroot environment (of `makechrootpkg`).
When debugging it is anyways annoying that `makepkg` sends the `gpg` output
to `/dev/null`. This way the logs are preserved.
Martchus