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 redox-os/kernel!135

Wrap borrows of page table entries in unsafe

See merge request redox-os/kernel!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 redox-os/kernel!134

Not sure if this is going to be required, and I'm not sure if this will
hurt performance, y'know, *always* doing this.

Simplify EXEC catching + add signal handling

See merge request redox-os/kernel!132

Instead of having a separate flag, let's reuse STOP_SINGLESTEP :)

I wasn't thinking enough when making this flag!

change seek sig to match posix - signed pos and result

See merge request redox-os/kernel!123

Changes required for GDB

See merge request redox-os/kernel!131

More complex physalloc

See merge request redox-os/kernel!127

Ptrace sane block

See merge request redox-os/kernel!129

Misc ptrace cleanup

See merge request redox-os/kernel!128