to 4. There is no need to be more strict at assembly time since we copy
the code anyway to a private page.
* Clear the direction flag and eflags. Probably not necessary but it won't
hurt to be safe.
* Add prefixes to all instructions to prevent any assembler mistakes.
* Remove zeroing of eax - edi. We use those registers immediately after
to transfer values to protected mode so this was pointless.
* Update comments to reflect info found during code review.
66b0070261