dashboard/builder: remove the repo export speed hack for hg

The builder will no longer generate a VERSION file, so we
can revert https://golang.org/cl/1405 once all builders
have updated.

Fixes golang/go#9296.

Change-Id: Ie51cb06a712157c16b231167f166b31d10ba8667
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/1510
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Chris Manghane <cmang@golang.org>
cmd/eg, godoc/redirect: update remaining code.google.com links

Change-Id: I67da9e0c0c511c19e5b5296fbcf46f641273a7bb
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/1515
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>