In another move to join with the age of the Fruitbat, increase SYSV
shared resources defaults beyond absolute minimums.

The new values are chosen mostly by magic. They are still fairly
small and will need increasing for large installations (especially
SHMMAX). However, they are now enough to e.g. start PostgreSQL
installations with ~~300 users and nearly 512 MB of shared buffers.

Reviewed by: A short discussion on hackers@