This CL is required for all.bat to work out of the box on
my Windows 8 laptop.

These tests either require the firewall to be turned off
or require the user to be in the Administrators group.
I don't know which.

Alex may follow up with a refinement of the test to
allow them to run if the user is in the Administrators
group.

Fixes #6392.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13421049