Refactor Linux packaging targets for better dependency tracking.

This makes sure Linux packages are rebuilt if any of the packaging scripts or
config files change.

Review URL: http://codereview.chromium.org/360017


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31001 0039d316-1c4b-4281-b951-d872f2087c98