Install the mingw OpenSSL package in Appveyor. This makes sure that
the OpenSSL headers and libraries match in Tor's Appveyor builds.

(This bug was triggered by an Appveyor image update.)

Fixes bug 32449; bugfix on 0.3.5.6-rc.

Bionic has a recent coccinelle version, which passes our CI tests.

But Bionic (and Xenial) cause permissions errors for chutney.
We'll fix those in 32240.

Part of 31919.

Closes ticket 32241.

`git merge --strategy ours` to take the 0.3.5 changes for 31001,
and ignore the conflicting 0.2.9 changes.

This build was added in 0.3.5.

We need to mitigate slow scheduling of Travis macOS jobs.

Closes ticket 32177.

Stem from maint-0.3.5, disabled macOS chutney from ticket32177_029.

We need to mitigate slow scheduling of Travis macOS jobs.

Closes ticket 32177.