go/printer: leave indentation alone when printing nodes from different files

ASTs may be created by various tools and built from nodes of
different files. An incorrectly constructed AST will likely
not print at all, but a (structurally) correct AST with bad
position information should still print structurally correct.

One heuristic used was to reset indentation when the filename
in the position information of nodes changed. However, this
can lead to wrong indentation for structurally correct ASTs.

Fix: Don't change the indentation in this case.

Related to issue 4300.

R=r
CC=golang-dev
http://codereview.appspot.com/6849066
net/http: reduce allocations in chunk reading & writing

R=golang-dev, r
CC=golang-dev
http://codereview.appspot.com/6847063
archive/zip, crypto/tls, net/http: Fix print format errors.

All of the errors were located using "go vet ./..." in "src/pkg".

R=golang-dev, iant
CC=golang-dev
http://codereview.appspot.com/6856056

Committer: Ian Lance Taylor <iant@golang.org>
archive/zip: handle extra data headers with no body

Fixes issue 4393.

R=golang-dev, bradfitz
CC=golang-dev
http://codereview.appspot.com/6854058
runtime/cgo: fix compilation on Windows with CFLAGS -Wall -Werror
also fix one out-of-date comment in cmd/ld/pe.c as well.

R=golang-dev, alex.brainman
CC=golang-dev
http://codereview.appspot.com/6843061
crypto/md5: speed up aligned writes and test/bench unaligned writes
Write() can safely use uint32 loads when input is aligned.
Also add test and benchmarks for unaligned writes.

Benchmark result obtained by Dave Cheney on ARMv5TE @ 1.2GHz:
benchmark                       old ns/op    new ns/op    delta
BenchmarkHash8Bytes                  4104         3417  -16.74%
BenchmarkHash1K                     22061        11208  -49.20%
BenchmarkHash8K                    146630        65148  -55.57%
BenchmarkHash8BytesUnaligned         4128         3436  -16.76%
BenchmarkHash1KUnaligned            22054        21473   -2.63%
BenchmarkHash8KUnaligned           146658       146909   +0.17%

benchmark                        old MB/s     new MB/s  speedup
BenchmarkHash8Bytes                  1.95         2.34    1.20x
BenchmarkHash1K                     46.42        91.36    1.97x
BenchmarkHash8K                     55.87       125.74    2.25x
BenchmarkHash8BytesUnaligned         1.94         2.33    1.20x
BenchmarkHash1KUnaligned            46.43        47.69    1.03x
BenchmarkHash8KUnaligned            55.86        55.76    1.00x

R=golang-dev, dave, bradfitz
CC=golang-dev
http://codereview.appspot.com/6782072
lib/godoc/codewalk.html: remove duplicate jquery inclusion
now we load jquery in its parent--godoc.html.

R=golang-dev, adg
CC=golang-dev
http://codereview.appspot.com/6814112
go/doc: fix identifier blank import handling for examples

Replacement CL for 6813061; thanks to minux for prototyping.

Fixes issue 4300.

R=minux.ma
CC=golang-dev
http://codereview.appspot.com/6782082
runtime: don't assume AT_RANDOM provide 4-byte aligned ptr

R=dave, remyoudompheng
CC=golang-dev
http://codereview.appspot.com/6854056
spec: fix constant expression example

Fixes issue 4400.

R=r, mirtchovski
CC=golang-dev
http://codereview.appspot.com/6782084