fixes Jira issue ROOT-183 and some minor change on FindGraphvix.cmake.


git-svn-id: https://root.cern.ch/svn/root/branches/v5-34-00-patches@49131 27541ba8-7e3a-0410-8455-c3a389f83636
merge from trunk http://root.cern.ch/viewvc?view=rev&revision=49133

Add flag to delete error array structure


git-svn-id: https://root.cern.ch/svn/root/branches/v5-34-00-patches@49134 27541ba8-7e3a-0410-8455-c3a389f83636