#GP in context switch stress build

This iso boots straight into a stress test of the context switch code.

For the debug console, execute mkfifo debugcon. In another terminal:

while true; do cat debugcon; done

...to watch debug output.

Here's an example qemu command line:

qemu-system-x86_64 -m 512M -s -cdrom dgos.iso -no-shutdown -no-reboot \
    -machine q35 -cpu kvm64 \
    -chardev pipe,path=debugcon,id=qemu-debug-out \
    -device isa-debugcon,chardev=qemu-debug-out \
    -smp cpus=4,cores=2,threads=1 -enable-kvm