amd64 buildworld cleanup

[Simon 'corecode' Schubert]

hey,

i sat down and fixed various issues so that a TARGET_ARCH=amd64 
buildworld run can now be completed.

Fetch the patch from <http://leaf.dragonflybsd.org/~corecode/amd64.diff> 
 and please review and comment.  I'd like to commit this in, say, 3 
days if nobody objects (possibly in smaller chunks).

Most of the patch is amd64 changes/additions, but some also affect i386 
(a short test showed no regressions).

Changes are heavily based on FreeBSD's amd64 port (with the exception of 
libc's math support, which is by NetBSD).  I want to thank the people 
who put so much effort in it and make it really easy for us to pick up a 
new port!

cheers
  simon
--
Serve - BSD     +++  RENT this banner advert  +++    ASCII Ribbon   /"\
Work - Mac      +++  space for low €€€ NOW!1  +++      Campaign     \ /
Party Enjoy Relax   |   http://dragonflybsd.org      Against  HTML   \
Dude 2c 2 the max   !   http://golden-apple.biz       Mail + News   / \