[FIX] search: Another go at wish4851 "Lost letter "G" in the search box" (rollback of r48364 which didn't work - possible php version differences involved in the behaviour of empty?)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@48558 b456876b-0849-0410-b77d-98878d47e9d5