There are reports of corruption. Let's disable it for now (for Go 1.6,
especially) until we can investigate and fix properly.

Update #13892

Change-Id: I557275e5142fe616e8a4f89c00ffafb830eb3b78
Reviewed-on: https://go-review.googlesource.com/18540Reviewed-by: Dave Cheney <dave@cheney.net>