This patch adds the openpty() and forkpty() library calls to posixmodule.c, when they are available on the target system. (glibc-2.1-based Linux systems, FreeBSD and BSDI at least, probably the other BSD-based systems as well.)

Lib/pty.py is also rewritten to use openpty when available, but falls back to the old SGI method or the 'manual' BSD open-a-pty code. Openpty() is necessary to use the Unix98 pty's under Linux 2.2, or when using non-standard tty names under (at least) BSDI, which is why I needed it, myself ;-)
forkpty() is included for symmetry.

The next patch includes suggested Doc-changes, but I'm not a TeX-y and haven't tested these additions.

See http://www.python.org/pipermail/patches/2000-June/000896.html and http://www.python.org/pipermail/patches/2000-June/000962.html for more information.