Set parent window for print dialog

In embedded LO this dialog sometimes shows up in background.

Change-Id: I9b7f423aaa6b2bbe915398287a5f3b955af930b4
Reviewed-on: https://gerrit.libreoffice.org/52962Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>

vcl/source/gdi/print3.cxx

@@ -473,7 +473,8 @@ bool Printer::PreparePrintJob(std::shared_ptr<PrinterController> xController,
     {
         try
         {
-            ScopedVclPtrInstance< PrintDialog > aDlg( nullptr, xController );
+            VclPtr<vcl::Window> xParent = xController->getWindow();
+            ScopedVclPtrInstance< PrintDialog > aDlg( xParent, xController );
             if( ! aDlg->Execute() )
             {
                 xController->abortJob();