* This should produce the same output while improving compatibility with systems that have a broken VGA implementation.
* Also fix an LD error with newer gcc toolchains.
* We distractedly chose to populate the message from our protective MBR
for GPT/UEFI-only boot media into the 4KB that directly followed the
MBR, which of course is space that is being used by the primary GPT.
* This resulted on systems having to fall back to using the secondary
GPT, which not all appear to be designed to do.
* Alter the code to ensure the protective message is written at LBA 34,
after the primary GPT.
* Closes#1507
* msg.S now reads an ASCII message (with escaped colour sequences)
from the following blocks, which is both more flexible and allows
for more content to be displayed.
* Also adds Bochs testing to the MBR build facility
* Adds an MBR to prompt the use about USB or HDD boot
* If USB boot is not selected, an INT13h override is added to
make the second bootable drive think it is first (0x81 -> 0x80)
* USB drive BIOS index is left unmodified
