Build `serve` doesn't actually serve anything when using Crostini on ChromeOS

[grouma]

Just playing around with running Linux apps on ChromeOS. Everything builds as expected but when I try to serve an example app nothing responds to the HTTP requests. I verified that a simple shelf server works so it appears the issue is in packag:build.

Dart VM version: 2.0.0-dev.53.0 (Unknown timestamp) on "linux_x64"
build_runner: 0.8.8
build: 0.12.5

[grouma]

Looks like setting the hostname to 0.0.0.0 resolves the issue. I know internally we changed all references from localhost to 0.0.0.0 as IPv6 rolled out. I'm wondering if this should be the default as well? Alternatively we can do what package:test does and checks for IPv6 support. @natebosch @jakemac53