The new revision is 389d49d4943780efbfcd2a434f4462b6d0f23c44 (Nov 13, 2015).
The runtimes are built using the new x/build/cmd/racebuild utility.
This update fixes a bug in race detection algorithm that can
lead to occasional false negatives (#10589). But generally just
brings in an up-to-date runtime.

Update #8653
Fixes #10589

Change-Id: I7ac9614d014ee89c2302ce5e096d326ef293f367
Reviewed-on: https://go-review.googlesource.com/16827Reviewed-by: Keith Randall <khr@golang.org>