runtime/race: RaceCond test is flaky

[aclements]

The RaceCond test has become flaky on the linux-amd64-race and freebsd-amd64-race builders. The current failures on the dashboard are:

2015-04-28T19:42:57-d3bd6b6/linux-amd64-race
2015-04-29T19:18:07-4d1ab2d/freebsd-amd64-race
2015-04-30T07:20:34-09edc5c/linux-amd64-race
2015-05-04T17:27:03-b79db4f/linux-amd64-race
2015-05-04T17:38:58-b86e71f/freebsd-amd64-race
2015-05-04T20:17:39-91938fd/linux-amd64-race
2015-05-06T19:40:38-17db6e0/linux-amd64-race

[gopherbot]

CL https://golang.org/cl/9803 mentions this issue.

[aclements]

This hasn't happened since the last dashboard failure I mentioned in my original comment. @dvyukov, did something happen to fix this? I don't see any changes to sync_test.go.

[dvyukov]

@aclements I did nothing.