test: internet/test-dns disable implicit ipv6

This ends up being too difficult to test across different deployments
net: fix listening on FDs on Windows

Fix a bug introduced by 3da36fe of a missed early return of a handle
that needed to be passed to listen.

Fixes test-net-listen-fd0.js on Windows
windows: fix module registration

The linker was optimizing the static variables that were supposed
to trigger module initialization.

I am making them non-static, and dllexport so that they don't get
optimized away.

Fixes #7116