AMD64-patch for buildworld

[Matthew Dillon]

:Simon,
:
:patch attached, totally 6. please apply them in order. commit message
:is in tar ball.
:
:for those who are interested: the buildworld cross-build completes
:with this patches and i am working on the cross-buildkernel. a slow,
:but still a progress :).
:
:yonghong

     The patches look great and large chunks of them look committable
     as well.

     I really want to make it possible to have both a 32 and 64 bit world
     installed simultaniously by using varsyms in critical places (i.e.
     /bin, /sbin, /usr/bin, /usr/sbin, /usr/pkg, /usr/lib, /usr/libexec,
     and so forth).  But it is probably too early to start worrying about
     that.
	
						-Matt