libmach: fix amd64 pe handling

Fixes issue 4841.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/7475046

Committer: Russ Cox <rsc@golang.org>
runtime,misc/cgo/test: disable broken tests so we can test the rest

R=golang-dev, minux.ma
CC=golang-dev
https://codereview.appspot.com/7486048

Committer: Russ Cox <rsc@golang.org>
A+C: Ewan Chou (individual CLA)

Generated by addca.

R=gobot
CC=golang-dev
https://codereview.appspot.com/7473047
strings: remove allocations in Split(s, "")

BenchmarkSplit1     77984460     24131380  -69.06%

R=golang-dev, rsc, minux.ma, dave, extemporalgenome
CC=golang-dev
https://codereview.appspot.com/7458043

Committer: Russ Cox <rsc@golang.org>