go/parser: Use test-specific filesets to avoid races.

Only affects test code.

Fixes issue 9025.
Fixes issue 9130.

LGTM=r, adonovan
R=adonovan, r
CC=golang-codereviews
https://codereview.appspot.com/180920043
cmd/go: fix running pprof on windows.

Fixes issue 9149.

LGTM=alex.brainman, rsc
R=rsc, dave, alex.brainman
CC=golang-codereviews
https://codereview.appspot.com/176170043

Committer: Russ Cox <rsc@golang.org>
image/jpeg: handle Read returning n > 0, err != nil in d.fill

Fixes issue 9127.

LGTM=r
R=bradfitz, r
CC=golang-codereviews, nigeltao
https://codereview.appspot.com/178120043
[dev.cc] all: merge default (95f5614b4648) into dev.cc

TBR=austin
CC=golang-codereviews
https://codereview.appspot.com/177220044