Fix file extension appending

src/QmlControls/QGCFileDialogController.cc

@@ -44,7 +44,7 @@ QString QGCFileDialogController::filenameWithExtension(const QString& filename,
 
     bool matchFound = false;
     for (const QString& extension : rgFileExtensions) {
-        QString dotExtension = QString(".%1").arg(extension);
+        QString dotExtension = QStringLiteral(".%1").arg(extension);
         matchFound = filenameWithExtension.endsWith(dotExtension);
         if (matchFound) {
             break;
@@ -52,10 +52,10 @@ QString QGCFileDialogController::filenameWithExtension(const QString& filename,
     }
 
     if (!matchFound) {
-        filenameWithExtension += rgFileExtensions[0];
+        filenameWithExtension += QStringLiteral(".%1").arg(rgFileExtensions[0]);
     }
 
-return filenameWithExtension;
+    return filenameWithExtension;
 }
 
 bool QGCFileDialogController::fileExists(const QString& filename)