net: make Dial fail faster on Windows closed loopback devices

net: make Dial fail faster on Windows closed loopback devices

On Windows when connecting to an unavailable port, ConnectEx() will
retry for 2s, even on loopback devices.

This CL uses a call to WSAIoctl to make the ConnectEx() call fail
faster on local connections.

Fixes #23366

Change-Id: Iafeca8ea0053f01116b2504c45d88120f84d05e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/495875
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>