[0.85] fix migration 84.1

git-svn-id: https://forge.indepnet.net/svn/glpi/branches/0.85-work@21624 35612d4c-9d10-0410-837c-bf9dd1be60d7
[0.85] delete_problem - fixed #4289

git-svn-id: https://forge.indepnet.net/svn/glpi/branches/0.85-work@21625 35612d4c-9d10-0410-837c-bf9dd1be60d7