patch: don't wait 5 seconds to re-read /etc/resolv.conf

[bradfitz]

If a Go process starts up, finds /etc/resolv.conf empty, then the DHCP
client writes /etc/resolv.conf, the Go program would find itself
broken for up to 5 seconds.

I fixed this in our Go fork at #92

Should upstream: yes, but haven't yet.

[bradfitz]

In ts1.24: a97b931