OpenBSD configuration for main platforms, framework

[Marc Espie]

This is the first patch of what's needed to configure egcs on the most
critical openbsd platforms (i386, m68k, sparc, and alpha), 
plus a config.guess patch so openbsd-*-hppa gets at least recognized...

Feel free to tweak the comments to reflect FSF copyright and remove
the $OpenBSD$ tags... I assume you've got some automatic mechanism to do 
that, and I don't want to attach n copies of this.

This patch includes main configure.in changes (for ALL openbsd platforms,
even ones which are not configured yet), main openbsd.h shared file,
t-openbsd, t-openbsd-thread fragments (under development for that one),
openbsd.ml/openbsd.mt fragments for libstdc++.


ChangeLog for gcc:

Tue Feb 16 18:30:13 CET 1999	Marc Espie <espie@cvs.openbsd.org>
	* configure.in : configure openbsd platforms
	* config.guess: recognize openbsd-*-hppa
	* config/openbsd.h: New file
	* config/xm-openbsd.h: New file
	* config/t-openbsd: New file
	* config/t-openbsd-thread: New file, experimental thread support

ChangeLog for libstdc++:

Tue Feb 16 18:30:13 CET 1999	Marc Espie <espie@cvs.openbsd.org>
	* configure.in: configure openbsd w & wo threads.
	* config/openbsd.{ml,mt}: fragments for our old ld.