Add support for 32bit PCI BIOS entry.

Add support for 32bit PCI BIOS entry.

Create a new code blob (code32seg) with support for 32bit functions
    that need to utilize explicit segment accesses.
This code blob uses global variables relative to %gs and with a
    dynamic code offset (determined by get_global_offset()).
Add BIOS32 structure and code.
Add code for 32bit PCI BIOS code.