synching with minios

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

While updating the OCaml runtime to 4.00 (which now boots!), I also looked at 
recent MiniOS changes, and found this:
http://xenbits.xen.org/hg/xen-unstable.hg/rev/c9f621893a05

...which adds floating point initialisation to MiniOS also.  This was the root 
cause of the floating point exceptions that Balraj was seeing when running Xen 
4.2 on i7 CPUs.  Always worth checking upstream first :)

I'm doing a quick sync of the MiniOS tree with ours too, while I'm here.  It's 
not quite so "mini" upstream anymore, with many many new drivers that we don't 
need, but there are some useful cleanups in the memory management layer as well.

-anil