fix unmaintained dependency and improve redox support

[auronandace]

Disclaimer: no AI tools were used in making this PR.

• Use directories crate instead of directories-next for the cache crate:
  • directories-next is unmaintained and calls redox-users 0.4 (which is outdated causing the default config file to not get generated).
  • directories is maintained and calls the up-to-date redox-users crate fixing config creation.
• Redox does not support DSYNC or RSYNC.
• Implement Redox x86_64 support for:
  • get_trap_registers()
  • store_handler_in_ucontext()
  • These require the bump in libc to 0.2.190 to access ucontext_t.

[pchickey]

This PR requires a maintainer to cargo vet new dependencies, some of which can probably be exempted because they only are used on the redox platform which isn't even in our Tier 3 support list. But, right now, I and other maintainers are dealing with several higher priority issues, so this may be one we have to come back to in a bit - thank you for your contribution and paitience.

[alexcrichton]

Looks like freebsd failed to build where the pinned version of mio doesn't build with the updated version of libc -- perhps fixed by a mio update?

[auronandace]

Can confirm, mio 1.2.4 fixes the freebsd issue with libc 0.2.190: tokio-rs/mio#2016

Do you need me to update the dependencie in this PR or should that be a maintainer job? I'm guessing that will need vetting too.

[bjorn3]

I believe there is going to be another libc release soon adding back the removed const as #[deprecated].

[pchickey]

@auronandace We'll make it your responsibility for Cargo.lock to have the correct deps in it that pass on all platforms, and then we will add whatever vets are required.

You can put the magic string "prtest:full" into a commit message so that the full test matrix runs on the PR, not just when it enters the merge queue. That should demonstrate that the freebsd failure is fixed and just vets are required to proceed.

[auronandace]

Looks like only 2 bumps were needed. mio for freebsd and rustix for apple.

Seems only rustix 1.1.4 to 1.1.5 needs vetting.