release.sh: simplify by removing usb option

	. relies on bios_wini which is long gone

Change-Id: I95257b6204cc6d928abcbd8492808b4b6450a99e
x86 hd image creator

A script that creates a HD image ready to be booted by an x86
emulator, ready to work in a crossbuild environment.

It's really just for qemu/kvm as there's no boot code in
the MBR and no bootloader installed so we rely on the in-kvm
multiboot implementation for now. This is very convenient for
passing args too.

To minimize reliance on external tools, we use the Minix
'partition' utility to write the partition table of the HD
image, which therefore has to be compiled natively.

	. new script releasetools/x86_hdimage.sh
	. natively compile minix 'partition' utility
	. make <machine/partition.h> 64-bit safe for it

Change-Id: If645b4691536752271e0b8a8ed59a34f248dace4