Needed for the header check to accept the header generated for
s390x as Go 1.2 style rather than Go 1.1 style.

Change-Id: I7b3713d4cc7514cfc58f947a45702348f6d7b824
Reviewed-on: https://go-review.googlesource.com/20966Reviewed-by: Minux Ma <minux@golang.org>