add_database: fail gracefully if too long db name
add_database: fail gracefully if too long db name

Truncating & adding can lead to fatal() later.

It was not an issue before, but with audodb (* in [databases] section)
the database name can some from network, thus allowing remote shutdown..

dbaxa/pgbouncer,dbaxa/pgbouncer,jaiminpan/pgbouncer,digoal/pgbouncer-x2,digoal/pgbouncer-x2,dbaxa/pgbouncer,digoal/pgbouncer-x2,kvap/pgbouncer,kvap/pgbouncer,jaiminpan/pgbouncer,dbaxa/pgbouncer,digoal/pgbouncer-x2,kvap/pgbouncer,jaiminpan/pgbouncer,wurenny/pgbouncer-x2,kvap/pgbouncer,jaiminpan/pgbouncer,wurenny/pgbouncer-x2,wurenny/pgbouncer-x2,wurenny/pgbouncer-x2