A+C: Aaron France (individual CLA)

Generated by addca.

R=gobot
CC=golang-dev
https://codereview.appspot.com/13073044
misc/emacs: Detect stale coverage reports

When the coverage report file is older than the file we're
showing the coverage report for, then we show a simple message
to state this fact.

R=adonovan, dominik.honnef, bradfitz
CC=golang-dev
https://codereview.appspot.com/12919044

Committer: Alan Donovan <adonovan@google.com>