In the tests, the runtime test fails after 2 minutes.
On an unloaded VM it only takes 45 seconds.
I think the difference is all the other build work going on
simultaneously with the running of the runtime test.

Change-Id: I41e95d2e4daea44ceaa8505f81aa7b5bcfa9ec77
Reviewed-on: https://go-review.googlesource.com/6364Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>