Replace llvm_asm with asm

See merge request !141

Support latest rust

See merge request !140

Thanks to @4lDO2 for all this. I just moved his changes to io_uring onto
the master branch of the kernel. I take no credit.

Implement funmap2

See merge request !139

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