Drawing: [skip ci] Fix several clazy issues:

* Missing reference in range-for with non trivial type [-Wclazy-range-loop-reference]
* Don't call QList::operator[]() on temporary [-Wclazy-detaching-temporary]
* Use multi-arg instead [-Wclazy-qstring-arg]

src/Mod/Drawing/Gui/DrawingView.cpp

@@ -509,7 +509,7 @@ void DrawingView::printPdf()
 
     if (dlg.exec() == QDialog::Accepted) {
         Gui::WaitCursor wc;
-        QString filename = dlg.selectedFiles().front();
+        QString filename = dlg.selectedFiles().constFirst();
         QPrinter printer(QPrinter::HighResolution);
         printer.setFullPage(true);
         printer.setOutputFormat(QPrinter::PdfFormat);