Printers, fix dialogs title (qt), issue 14186

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41117 4005530d-fff6-0310-9dd1-cebe43e6787f
Printers, dialogs, if Title='' use DefaultTitle like in qt, (cups/linux)

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41118 4005530d-fff6-0310-9dd1-cebe43e6787f