Update README - copy *.aml files for QEMU.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Add dependencies to vgafixup.py and buildversion.sh scripts.

Rebuild targets if these scripts change.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Set ZF prior to keyboard read call in check_for_keystroke().

Set the ZF flag to make sure the keyboard interrupt is actively
clearing it on a key event.  This fixes a hang when CONFIG_BOOTMENU is
on and CONFIG_KEYBOARD is off.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>