Implement auxiliary vector

See merge request !136

Mainly because I think the code could be cleaner if we can remove
support entirely :)

I was an idiot and forgot rbx wasn't always backed up. As a result, we
should never ever write to it

Catch kernel signal

See merge request !135

Wrap borrows of page table entries in unsafe

See merge request !126

I think we need to reimplement these functions in assembly :(

It's broken on master anyway

Because the way we were using inline assembly was technically incorrect
and breaking the laws of rust

This *finally* compiles. That doesn't mean it works!

Don't panic on mprotect for unmapped pages

See merge request !134