Port rombios32 code from bochs-bios.

Port rombios32 code from bochs-bios.

This adds acpi, smbios, pci init, etc.
Changes from original rombios32.c code:
* Header file translation.
* Use common functions already in code (eg, outb, memset, bios_printf,
  usleep)
* Implement trampoline for disabling bios shadowing (rombios32 code
  actually runs in the 0xf0000 area).
* Copy asm code from rombios32start.S to an asm() statement in C
  code.