These are quite a bit faster than on AppVeyor (with ccache about a fifth,
without less than half - and they run concurrently).
We only keep the AppVeyor builds for now to test against those old
OpenSSL versions (1.1.1 and 1.0.2) for which there is still extended
support available. Even simplified like that they still take longer
than the builds on GA.
Tobias Brunner
19d73ef156