[info] libc CI is back online

[gnzlbg]

Small update: libc CI is back online and is now mainly only using Azure Pipelines on the rust-lang2 organization - the configuration file is in ci/azure.yml. Good news is, it appears to have less spurious failures than Travis/Appveyor, jobs get cancelled quicker, less resources are wasted, etc. Bad news is that the org currently only has ~10 concurrent jobs (cc @pietroalbini), so each CI job takes a long while. I know that for most of you, the only real way to test a PR is to let it fully run through CI. We currently allow for some concurrency here, by only spawning tasks one previous checks have passed. Because we have so little concurrency, if you are working on a WIP PR, and need to only test a particular target, please disable all others manually by commenting them out in the ci/azure.yml file, at least until we merge most of the PRs in the queue. If you discover any issues with Azure, have any ideas about how to make things faster, etc. please ping me somewhere.

Now, there are a lot of PRs open that have been reviewed and approved. I'm going to start merging them in FIFO order (from oldest to newest), it might take a week till all of them are merged. One of the latest is @jackpot51 PR updating libc to 0.2.61. I will do a release after that one is merged, independently of what happens in between. If you need a new release sooner, please let me know, and I'll squeeze one in. Also, if some of the PRs in the queue is blocking a PR in rust-lang/rust, please do also let me know, and I will prioritize those over the others to unblock further work upstream.

@jackpot51 @asomers @semarie @jbaublitz @mati865 @xen0n @equal-l2 @atouchet @Gymmasssorla @pizzaming @jdm @fintelia @BaoshanPang