Add CI support to get releases built automatically

[sbc100]

We could use circle-ci or travis-ci. They both allow for long builds like this now (travis limit is 50 minutes and I think circle-ci is 5 hours!).

We could also add PR testing, although it might be annoying long..

[pchickey]

@tschneidereit has done some work on using azure pipelines for this in wasi-libc. My understanding is that azure works quite well, and is free of charge. I don't think its a good idea to build new systems on travis-ci- they have hemorrhaged senior staff over a labor dispute post buy-out, and don't have the best uptime.

[sbc100]

I'm not wedded to any CI system. As long as it can publish to github releases and has a high enough timeout to handle the llvm build.

[tschneidereit]

I've done some work on getting Azure Pipelines working, yes. Unfortunately I haven't been able to get the Windows build working, but mac and Linux both work: https://dev.azure.com/tschneidereit/WASI%20SDK/_build/results?buildId=86

Adding releases will be relatively easy based on this, and the timeout is very generous (I think 5 hours), so we won't run into any issues there.

[tschneidereit]

Oh, and I think it'd be fine to land this with Windows disabled for now, or at least made to not fail the overall check. I can set up an Azure org for that.

[sbc100]

Yes, lets get a proof of concept landed and we can add windows + releases later.

[tschneidereit]

Yes, lets get a proof of concept landed and we can add windows + releases later.

This has, now happened, and #48 was the first PR that passed this CI setup. I plan to work on adding releases sometime in the next two weeks, but if anyone beats me to it, I'd not be sad :)

[abrown]

This already works; see the GitHub workflow and associated ci scripts.