windows: avoid breaking Libc.getuid call

[will]

partially address #291

@jwoertink does this make it not crash at least? I don't have a windows install to test on myself

[jwoertink]

I think this might work... I'm now getting a different compiler error though...

I assume this isn't PG related.

Showing last frame. Use --error-trace for full trace.

In D:\a\_temp\crystal-latest-true-undefined\src\openssl\ssl\socket.cr:150:33

 150 | raise OpenSSL::SSL::Error.new(@ssl, bytes, "SSL_write")
                                 ^--
Error: Error: instance variable '@underlying_eof' of OpenSSL::SSL::Error must be Bool, not Nil
Error: Process completed with exit code 1.

[will]

underlying_eof I don't think appears at all in this codebase. It could be something here is triggering that to be nil, I suppose, but I can't think of what that'd be

[jwoertink]

I've been able to confirm that the error I got is not related to PG. I've found a fix and confirmed this patch does fix the original issue letting Avram compile on Windows.