Signed-off-by: Joe Richey <joerichey@google.com>

* Update to wasi 0.11

The main breaking change between v0.10 and v0.11 is that Error is
removed in favour of Errno. Unfortunately we can't create an Errno from
outside the wasi create so we're loosing some debug information for
errors.

I've opened an issue to add back such a constructor, see
<bytecodealliance/wasi-rs#64>.

* Use libc::strerror to get the error message on wasi

Since wasi v0.11 doesn't (yet) provided a way to create Errno, see
<bytecodealliance/wasi-rs#64>.

* Remove libc dependency for WASI

This does mean that we won't get an error message for the error type.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

This allows Strict Provenance to work properly, fixing #262. It also
now matches what `libstd` does:
https://github.com/rust-lang/rust/blob/9f7e997c8bc3cacd2ab4eb75e63cb5fa9279c7b0/library/std/src/sys/unix/weak.rs#L85-L141

Also, while reading the `libstd` code, I noticed that they use an
`Acquire` fence and `Release` store as the returned pointer should
have "consume" semantics. As this doesn't yet exist in Rust, we
instead do exactly what `libstd` does, which means:
  - Relaxed Load
  - Release Store
  - Acquire fence when returning pointer

Signed-off-by: Joe Richey <joerichey@google.com>

Co-authored-by: Joe ST <joe@fbstj.net>

Signed-off-by: Joe Richey <joerichey@google.com>