- obtained by running sh vendor.bash
- contains updated tests and some bug fixes for Montgomery mult.
  (not used by compiler)
- for consistency of math/big versions only

Change-Id: Ib47e48d5b7f6d0e05d7837b1bc74bdb03f2b094e
Reviewed-on: https://go-review.googlesource.com/18831
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>