Qt: Make the checkSaveAsWithComment dialog box appear.

Set the parent of the QMessageBox in the constructor instead of calling
QMessageBox::setParent(). The latter inherits from QDialog, and it
"clear[s] the window flags specifying the window-system properties for
the widget (in particular it will reset the Qt::Dialog flag)."
(See https://doc.qt.io/qt-5/qdialog.html#details )
This makes the dialog properly appear instead of attempting to save a file
with comments to a file type that does not support comments silently failing.
Fixes #17146.


(cherry picked from commit fb422bed91)

ui/qt/capture_file_dialog.cpp

@@ -117,11 +117,10 @@ check_savability_t CaptureFileDialog::checkSaveAsWithComments(QWidget *parent, c
         return SAVE;
     }
 
-    QMessageBox msg_dialog;
+    QMessageBox msg_dialog(parent);
     QPushButton *save_button;
     QPushButton *discard_button;
 
-    msg_dialog.setParent(parent);
     msg_dialog.setIcon(QMessageBox::Question);
     msg_dialog.setText(tr("This capture file contains comments."));
     msg_dialog.setStandardButtons(QMessageBox::Cancel);