build, cmd/5l: actually report failures for -linkmode tests

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/7938046
all.bat,make.bat,run.bat: make these work even when directory has space in it

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7510048
net: disable tests with controlling network facilities in short mode

Perhaps it would make FreeBSD 10-CURRENT/ARM on Raspberry Pi builders happy.

R=golang-dev, dave
CC=golang-dev
https://codereview.appspot.com/8008043
net/http: deflake BenchmarkServerFakeConnNoKeepAlive.

Fixes issue 5121.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7814046
cmd/cc, cmd/ld: do not overflow strings in symbol lookup.

R=golang-dev, dave, minux.ma
CC=golang-dev
https://codereview.appspot.com/7876044