Upgrade FreeBSD's CI image to release 11.3

skip roundtrip on few structs on OpenBSD

skip roundtrip on some structs on OpenBSD. it is mostly the same than other targets: dirent, utsname, utmp.

define KERN_TIMEOUT_STATS and incr KERN_MAXID on OpenBSD

`KERN_TIMEOUT_STATS` has been defined in [sys/sysctl.h (1.194)](https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/sys/sysctl.h?rev=1.194&content-type=text/x-cvsweb-markup)

Add IP_RECVERR (unix/linux_like/mod.rs)

Setup Azure Pipelines

cc @alexcrichton this needs enabling Azure Pipelines for this repo

The 11.3-release GCE image isn't working due to a bug in the included
py36-google-compute-engine package, but that bug is fixed in the latest
stable/11 images.

Add support for hexagon-unknown-linux-musl

Increase Redox & Relibc support

- Add a lot of constants from relibc
- Fix the timezone not found error found previously on Redox
- Wrap WIFEXITED _et al._ in an unsafe block to match the rest of the API
- Add support for the extra_traits feature and Redox
- Fmt

cc @jackpot51

Update wasmtime to the latest master.

The previous wasmtime revision is broken because one of its dependencies, `memoffset` 0.3, was yanked, which appears to make it unavailable. This was fixed by downgrading to `memoffset` 0.2.

Disable testing that thumbv6m-none-eabi builds properly