exit(3) on Linux

The text 56a4b7ce62c8, as Debian 2.2 (Potato), Debian 2.1 (Slink), Debian 2.0 (Hamm), Debian 1.3 (Bo), Debian 1.2 (Rex), Debian 1.1 (Buzz) shipped it.

cause normal program termination

exit(3) on Linux now