cmd/go: use filepath.SplitList when inspecting GOPATH

There exists a test case for this condition, but it only runs on unix systems, which neatly dovetails into the code always using ':' as the list separator.

R=adg, iant
CC=golang-dev
https://codereview.appspot.com/7057052
cmd/gc: fix uintptr(nil) issues.

A constant node of type uintptr with a nil literal could
happen in two cases: []int(nil)[1:] and
uintptr(unsafe.Pointer(nil)).

Fixes issue 4614.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/7059043
spec: s/char_lit/rune_lit/

The spec talks explicitly about rune literals but the
respective production is still called char_lit for
historic reasons. Updated the two occurences.

Fixes issue 4602.

R=rsc, iant, r, ken
CC=golang-dev
https://codereview.appspot.com/7070048
A+C: Jason Travis (individual CLA)

Generated by addca.

R=gobot
CC=golang-dev
https://codereview.appspot.com/7064054
cmd/vet: fix doc typo.

R=golang-dev, dsymonds
CC=golang-dev
https://codereview.appspot.com/7061050

Committer: David Symonds <dsymonds@golang.org>
net/http/cgi: make it work without REQUEST_URI environment variable

Fixes issue 4367.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7062052