Partially fixes issue 3718.

R=golang-dev, rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6300043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6341046

Note url.Error wrapping, and s/issue/issuing/.

Fixes #3724

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6294093

        We need to use kernel headers to generate defs_linux_$GOARCH.h

R=golang-dev, dave, alex.brainman, iant
CC=golang-dev
https://golang.org/cl/6296091

Several of my students were confused by trying to use both the error
return and a reply return, so I figured it was worth explicitly clarifying
that returning an error overrides the reply.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6327051

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6325053

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6337047

Use code to be used in lisp programs as suggested in the doc strings for
replace-{string|regexp}. Bonus: This code works for XEmacs.

R=golang-dev, sameer, jmeurin
CC=golang-dev
https://golang.org/cl/6296073

Flame motivated me to get around to adding extended key usage support
so that code signing certificates can't be used for TLS server
authentication and vice versa.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6304065

based on UCA test files.

R=r
CC=golang-dev
https://golang.org/cl/6216056

        Fixes #3753.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6304097

        if we were to use sizeof(sa.sa_mask) instead of 8 as the last argument
        to rt_sigaction, we would have already fixed this bug, so also updated
        Linux/386 and Linux/amd64 files to use that; also test the return value
        of rt_sigaction.

R=dave, rsc
CC=golang-dev
https://golang.org/cl/6297087

If the server replies with an HTTP response before we're done
writing our body (for instance "401 Unauthorized" response), we
were previously ignoring that, since we returned our write
error ("broken pipe", etc) before ever reading the response.
Now we read and write at the same time.

Fixes #3595

R=rsc, adg
CC=golang-dev
https://golang.org/cl/6238043

Also, fixes one violation found during testing where both
response and error could be non-nil when a CheckRedirect test
failed.  This is arguably a minor API (behavior, not
signature) change, but it wasn't documented either way and was
inconsistent & non-Go like.  Any code depending on the old
behavior was wrong anyway.

R=adg, rsc
CC=golang-dev
https://golang.org/cl/6307088

R=rsc, dsymonds
CC=golang-dev
https://golang.org/cl/6303099

R=r
CC=golang-dev
https://golang.org/cl/6301096

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6303098

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6312045

A comment to that effect was introduced
with rev d332f4b9cef5 but the respective
code wasn't deleted.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6304086

        Fixes #3716.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6310044

R=r, dsymonds
CC=golang-dev
https://golang.org/cl/6298085

        Fixes #3739.

R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6295083

        Fixes #3735.

R=golang-dev, agl
CC=golang-dev
https://golang.org/cl/6301083

R=golang-dev, rsc, dsymonds, minux.ma
CC=golang-dev
https://golang.org/cl/6305089

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6298079

GOARCH=amd64 benchmarks

src/pkg/runtime
benchmark                  old ns/op    new ns/op    delta
BenchmarkConvT2ESmall             10           10   +1.00%
BenchmarkConvT2EUintptr            9            0  -92.07%
BenchmarkConvT2EBig               74           74   -0.27%
BenchmarkConvT2I                  27           26   -3.62%
BenchmarkConvI2E                   4            4   -7.05%
BenchmarkConvI2I                  20           19   -2.99%

test/bench/go1
benchmark                 old ns/op    new ns/op    delta
BenchmarkBinaryTree17    5930908000   5937260000   +0.11%
BenchmarkFannkuch11      3927057000   3933556000   +0.17%
BenchmarkGobDecode         21998090     21870620   -0.58%
BenchmarkGobEncode         12725310     12734480   +0.07%
BenchmarkGzip             567617600    567892800   +0.05%
BenchmarkGunzip           178284100    178706900   +0.24%
BenchmarkJSONEncode        87693550     86794300   -1.03%
BenchmarkJSONDecode       314212600    324115000   +3.15%
BenchmarkMandelbrot200      7016640      7073766   +0.81%
BenchmarkParse              7852100      7892085   +0.51%
BenchmarkRevcomp         1285663000   1286147000   +0.04%
BenchmarkTemplate         566823800    567606200   +0.14%

I'm not entirely sure why the JSON* numbers have changed, but
eyeballing the profile suggests that it could be spending less
and more time in runtime.{new,old}stack, so it could simply be
stack-split boundary noise.

R=rsc, dave, bsiegert, dsymonds
CC=golang-dev
https://golang.org/cl/6280049

Fixes a situation where a nested bad type would still
permit the outer type to install a working engine, leading
to inconsistent behavior.

Fixes #3273.

R=bsiegert, rsc
CC=golang-dev
https://golang.org/cl/6294067

Thanks to Håvid Falch for finding the problem.

Fixes #3414

R=r, rsc
CC=golang-dev
https://golang.org/cl/6300081

benchmark                  old ns/op    new ns/op    delta
BenchmarkAtof32Decimal           215           73  -65.72%
BenchmarkAtof32Float             233           83  -64.21%
BenchmarkAtof32FloatExp         3351          209  -93.76%
BenchmarkAtof32Random           1939          260  -86.59%

R=rsc
CC=golang-dev, remy
https://golang.org/cl/6294071

Also: better GCD tests.

R=rsc
CC=golang-dev
https://golang.org/cl/6295076

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6301076

Fixes #3454.

R=rsc
CC=golang-dev
https://golang.org/cl/6305069

A comment map associates comments with AST nodes
and permits correct updating of the AST's comment
list when the AST is manipulated.

R=rsc
CC=golang-dev
https://golang.org/cl/6281044

!(linux&cgo | darwin&cgo)
= (!linux|!cgo) & (!darwin|!cgo)
= (!linux&!darwin) | !cgo  // new comment
≠ !linux | !darwin | !cgo  // old comment

Fixes #3726.

R=golang-dev, bsiegert
CC=golang-dev
https://golang.org/cl/6306076

Fixes #3695.

R=r, dave, rsc
CC=golang-dev
https://golang.org/cl/6304062

R=rsc
CC=golang-dev
https://golang.org/cl/6297085

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/6295072

benchmark                    old ns/op    new ns/op    delta
BenchmarkGCD10x10                 4383         2126  -51.49%
BenchmarkGCD10x100                5612         2124  -62.15%
BenchmarkGCD10x1000               8843         2622  -70.35%
BenchmarkGCD10x10000             17025         6576  -61.37%
BenchmarkGCD10x100000           118985        48130  -59.55%
BenchmarkGCD100x100              45328        11683  -74.23%
BenchmarkGCD100x1000             50141        12678  -74.72%
BenchmarkGCD100x10000           110314        26719  -75.78%
BenchmarkGCD100x100000          630000       156041  -75.23%
BenchmarkGCD1000x1000           654809       137973  -78.93%
BenchmarkGCD1000x10000          985683       159951  -83.77%
BenchmarkGCD1000x100000        4920792       366399  -92.55%
BenchmarkGCD10000x10000       16848950      3732062  -77.85%
BenchmarkGCD10000x100000      55401500      4675876  -91.56%
BenchmarkGCD100000x100000   1126775000    258951800  -77.02%

R=gri, rsc, bradfitz, remyoudompheng, mtj
CC=golang-dev
https://golang.org/cl/6305065

R=sameer
CC=golang-dev
https://golang.org/cl/6296060

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6302069