amd64 64-bit work starting

[Matthew Dillon]

    I am starting on the amd64 64 bit work now.  I'm guess it will
    take all of February to do, possibly longer since I am going 
    on a mini-vacation this coming week (but I'll have connectivity).

    Most of the initial work is going to be precursor and infrastructure
    work.  e.g. building the cross compiler, cleaning up various programs,
    system configuration files, and so forth.  I intend to write the 
    majority of the kernel code from scratch but will definitely be using
    the FreeBSD work as a template for a good chunk of it.  I expect,
    however, that the mmu topology and code will wind up being completely
    different in DFly.

    The rough sequence of events:

	* build support and cross compilation work
	* kernel build
	* boot 64-bit kernel almost to single user
	* 32 bit userland support
	* boot kernel to single user
	* basic device driver and filesystem testing
	* boot kernel to multi user
	(fully working system at this point)
	* everyone w/ 64 bit boxes start banging on it, fixing additional
	  device drivers, get 64 bit buildworlds working, and so forth.

						-Matt