Build: Enable SSL in mingw by linking against WinSSL

The mingw builds aren't submitting telemetry because the curl library
they are linked against is configured to use openSSL and openSSL looks
for the certificates in the users home folder. This keeps it from
contacting web services because it can't communicate over SSL.

This commit adds a download in mingw builds that will download a
precompiled curl for mingw linked against winssl and sspi.