From Christian Holm:

- configure: new option --fail-on-missing, when this is set configure
  will fail if the files for a requested plugin are not found. Needed
  for proper Debian install.
- many Debian packaging fixes.


git-svn-id: http://root.cern.ch/svn/root/trunk@16103 27541ba8-7e3a-0410-8455-c3a389f83636