This commit migrates wasmtime's CI infrastructure from Azure Pipelines
to Github Actions. Using Github Actions has a few benefits over other
offerings:
* Being natively integrated with Github means that there's no degree of
user account configuration or access control management, it's all
inherent via already existing Github permissions.
* Github Actions gives 20 parallel builders instead of Azure's 10 by
default, which is a nice boost to have!
Overall I've found Github Actions to feel a bit cleaner than Azure
Pipelines as well. Subjectively I've found the configuration to be more
readable and more pleasant to work with, although they're both just as
"powerful" I think. Additionally Github Actions has been pretty solid in
my own personal testing for a number of other projects.
The main trickiness with wasmtime's CI is the rolling `dev` release of
the master branch as well as binary releases for tags. Github Actions
doesn't have quite as much built in functionality as Azure Pipelines,
but Github Actions does have a nice feature where you can define the
code for an action locally rather than only using built-in actions.
This migration adds three local actions with some associated JS code to
run the action (currently it looks like it basically requires JS)
* An `install-rust` action papers over the gotchas about installing
Rust, allowing Rust installation to be a one-liner in the configuration.
* A `binary-compatible-builds` action allows easily configuring the
wheels and the binaries to be "more binary compatible" and handles
things like compilation flags on OSX and Windows while handling the
`centos:6` container on Linux.
* The `github-release` action is the logic using the `@actions/github`
JS package to orchestrate the custom way we manage rolling releases,
ensuring that a new release is made for the master branch under `dev`
(deleting the previous tag/release ahead of time) and then also
manages tagged releases by uploading them there.
I'm hoping that most of the inline actions here will largely go away.
For example `install-rust` should be simply `rustup update $toolchain`
once various environment issues are fixed on Github Actions runner
images. Additionally `github-release` will ideally migrate to something
like https://github.com/actions/create-release or similar once it has
enough functionality. I'm also hoping that the maintenance in the
meantime of these actions is pretty low-cost, but if it becomes an issue
we can look into other solutions!
* Use generated type bindings.
Use the witx API descriptions to generate the bulk of the contents of
host.rs, wasi.rs, and wasi32.rs.
This also prunes out many of the miscellaneous libc definitions from
those files which aren't currently in use by wasi-common. If there's
anything removed that's still needed by someone, it's easy to add things
back in.
* Remove unneeded iovec conversion routines.
