fmt: fix documentation for %g and %G
It now echoes what strconv.FormatFloat says.

Fixes issue 9012.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://codereview.appspot.com/169730043
cmd/gc: fix internal compiler error in struct compare

Fixes issue 9006.

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/167800043
cmd/objdump: disassemble local text symbols

Fixes issue 8803.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/169720043

Committer: Russ Cox <rsc@golang.org>