Update dependencies for rust 2022-03-18.

See merge request !342

Initialize TLS manually on Redox as Linux does.

See merge request redox-os/relibc!340

wctype

See merge request redox-os/relibc!339

Update toolchain

See merge request redox-os/relibc!338

This also replaces all the assembly that previously used the AT&T style
with the (in my opinion) superior Intel syntax.

I tried prepending `.att_syntax prefix`, but that did not work...