Upgrade Linux to 3.16.0-4, i.e. 3.16.7-1.
Revert "Fetch Linux 3.16-3 packages from testing (Closes: #8248)."

This reverts commit b010387958efa192f308ae3837c7f6d723054d88.
Merge remote-tracking branch 'origin/feature/linux-3.16.0-4' into stable