bytes: annotate assembly functions with //go:noescape

R=golang-dev, agl, bradfitz, rsc
CC=golang-dev
https://codereview.appspot.com/7299064
crypto/x509: allow MS/NS SCG key usage as ServerAuth.

By default, crypto/x509 assumes that users wish to validate
certificates for ServerAuth. However, due to historical reasons,
COMODO's intermediates don't specify ServerAuth as an allowed key
usage.

Rather NSS and CryptoAPI both allow these SGC OIDs to be equivalent to
ServerAuth.

R=rsc
CC=golang-dev
https://codereview.appspot.com/7312070
testing: be explicit about use of b.N

R=golang-dev, minux.ma
CC=golang-dev
https://codereview.appspot.com/7314071
crypto/x509: disable SCG test with system validation.

On Windows, CryptoAPI is finding an alternative validation path. Since
this is a little non-deterministic, this change disables that test
when using system validation.

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/7313068
spec: clarify that f(g()) requires that g return >= 1 value

Fixes issue 4573.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7322043
net/http: more request benchmarks

Add benchmarks for common http benchmarking tools. The intent is to catch optimisations which favor synthetic benchmarks that do not show improvements for real clients like Chrome.

BenchmarkReadRequestChrome        200000             10133 ns/op          60.29 MB/s        3148 B/op         32 allocs/op
BenchmarkReadRequestCurl          500000              4314 ns/op          18.08 MB/s         905 B/op         15 allocs/op
BenchmarkReadRequestApachebench   500000              4363 ns/op          18.79 MB/s         956 B/op         16 allocs/op
BenchmarkReadRequestSiege         500000              6408 ns/op          24.19 MB/s        1397 B/op         22 allocs/op
BenchmarkReadRequestWrk          1000000              2838 ns/op          14.09 MB/s         757 B/op         11 allocs/op

R=golang-dev, bradfitz
CC=golang-dev, haimuiba
https://codereview.appspot.com/7300075