test: pummel/net-connect-econnrefused backoff

We were trying too hard to connect, and getting timeouts instead of
the refusals, slow down how hard we try.
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

See https://github.com/joyent/node/issues/7116

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.