I am finding it useful to be able to pretty print Mappers and
ActivePageTable structs.

Signed-off-by: Wren Turkal <wt@penguintechs.org>

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

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 !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 !123

Changes required for GDB

See merge request redox-os/kernel!131

More complex physalloc

See merge request !127

Ptrace sane block

See merge request !129