Almost ready inline kernel booter

[Daniel Jacobowitz <youngdrow%geocities.com@localhost>]

Since Apple OF doesn't seem to like OF_open() very much, I'm adding 
support for kernels embedded in the XCOFF file.  It's almost ready - one 
PMac specific bug left, I think.  It default catches when reading the 
xcoff headers, after "Beginning image search."

If anyone wants to offer opinions, there are:
http://www.drow.net/netbsd/ofwboot (or .tar.gz) [the original]
http://www.drow.net/netbsd/ofwmac (or .tar.gz) [the new]
http://www.drow.net/netbsd/linux_arch_ppc (or .tar.gz)
         [the linux/ppc working one, see in coffboot/]

The only difference I see between mine and linuxppc's is i do not map 
8MB of ram to 0xC0000000, but I do not think that is necessary at this 
stage in the boot.   Ideas?

Please send any comments/suggestions/bugfixes/flames/etc.

Dan