[release-branch.go1.8] crypto/elliptic: fix carry bug in x86-64 P-256 implementation.
Patch from Vlad Krasnov and confirmed to be under CLA.
Fixes #20040.
Change-Id: Ieb8436c4dcb6669a1620f1e0d257efd047b1b87c
Reviewed-on: https://go-review.googlesource.com/41070
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit
9294fa2749ffee7edbbb817a0ef9fe633136fa9c)
Reviewed-on: https://go-review.googlesource.com/43770
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>