These rules trigger 116 times while running make.bash.
And at least for the sample code at
https://github.com/golang/go/issues/18906#issuecomment-277174241
they are providing optimizations not already present
in amd64.

Updates #18906

Change-Id: I410a480f566f5ab176fc573fb5ac74f9cffec225
Reviewed-on: https://go-review.googlesource.com/36217
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>