This commit performs a number of updates for libc with the `wasm32-wasi`
target:

* Updates the `wasi-libc` repository commit used (previously known as
  `wasi-sysroot`)
* Updates the container to Ubuntu 19.10 which has Clang 9 packaged which
  is all we need.
* Avoids building `wasmtime` and instead downloads a precompiled binary.
* Updates bindings in `src/wasi.rs` to match the current upstream state.

Co-Authored-By: gnzlbg <gnzlbg@users.noreply.github.com>

Signed-off-by: patrick felt <patrick.felt@sling.com>

initial work from @landryb for OpenBSD, various fixes and NetBSD support from me.

Fixes #1585

Signed-off-by: Arthur Gautier <baloo@gandi.net>

Signed-off-by: Arthur Gautier <baloo@gandi.net>

First batch for #1562

This adds libc-test support for Freebsd10 and a CI build job that tests
FreeBSD10 with LIBC_CI only.

Currently, libc supports and detects freebsd11 and freebsd13
Unknown versions, like freebsd13, is treated as freebsd11.
This patch solve the issues, detecting freebsd13 and treating it like
freebsd12.
Inverting the logic not(freebsd12) -> freebsd11 where possible

Currently, libc supports and detects freebsd11 and freebsd13
Unknown versions, like freebsd13, is treated as freebsd11.
This patch solve the issues, detecting freebsd13 and treating it like
freebsd12.
Inverting the logic not(freebsd12) -> freebsd11 where possible

These constants have already been deprecated for a few releases with
a deprecation notice, so they can finally be removed.

Closes rust-lang/libc#665

Per discussion in #1410, this is necessary to avoid struct size mismatches between Rust and C on
systems with glibc < 2.28.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

This was added in Linux 5.1 and will only show up in the next glibc
release, thus skip in tests.