4.4BSD snapshot (revision 8.1); add 1993 to copyright

exp__D, exp__E, log__D, and log__L are private; prepend leading "__"

Fixed behavior for subnormal returns.

new version from Peter McIlroy; note, funded by UUNET

original version from Peter McIlroy
date and time created 92/12/02 15:29:28 by bostic