wgengine/netstack: use inet.af/netstack, remove 64-bit only limitation

This reverts the revert commit 84aba349d9.

And changes us to use inet.af/netstack.

Updates #1518

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f