Fix build for FreeBSD and Windows

[christopher-henderson]

In order to release v3.7.0 we had to opt out of building against FreeBSD and Windows.

These miscompilations were emitted by zcrypto so that would be the place to start.

[mhyder13]

I have a Windows build working locally with a hack I set up when this first started failing, but I'm not sure if there is a path from that to doing a working release build. I'm sharing it hare as a workaround for anyone who needs a Windows build of the latest zlint version and can't wait for a better fix.

I've set up a go workspace with only zlint and zcrypto. Make sure to set your local zcrypto repo to the same commit as is expected by zlint or it won't compile. I then made one local edit to zcrypto to bypass the compilation error. I copied root_unix.go, set it to be used for Windows builds, and hard-coded it to load system roots from a pem file on my local machine. I used a dump of my Windows local root store, but I don't think this matters. Zlint doesn't actually use the root store functionality of zcrypto, so it's probably possible to do this with a simpler version of the root file that just stubs out this functionality, though I didn't test that.

I've been using this for some of my local development and all the zlint unit and integration tests pass in this configuration. I haven't encountered any compatibility issues with this configuration yet.

You should not expect zcrypto to work properly as a TLS library with this configuration, even if you do dump your local root store into the file. Windows loads roots from the mothership dynamically on first use, so your local root store is more reflective of your browsing habits than the full Microsoft root program. I didn't do a full deep dive on what it would take to make something like this work for a release build or to do a real fix for zcrypto.