Jenkins Windows builders are currently broken

Weasel just mentioned in #tor-project that our Jenkin windows builders have been failing for a while.

I suspect the issue might be related to a missing libssp-0.dll, which we handle nicely with appveyor using:

Copy-Item "C:/msys64/${env:compiler_path}/bin/libssp-0.dll" -Destination "${env:build}/src/test"
Copy-Item "C:/msys64/${env:compiler_path}/bin/zlib1.dll" -Destination "${env:build}/src/test"