Fix enabling Andvanced Tuning crash

src/QGCApplication.cc

@@ -158,7 +158,11 @@ static QObject* shapeFileHelperSingletonFactory(QQmlEngine*, QJSEngine*)
 }
 
 QGCApplication::QGCApplication(int &argc, char* argv[], bool unitTesting)
+  #if defined(__mobile__)
     : QGuiApplication           (argc, argv)
+  #else
+    : QApplication              (argc, argv)
+  #endif
     , _runningUnitTests         (unitTesting)
 {
     _app = this;

src/QGCApplication.h

@@ -51,8 +51,15 @@ class QGCFileDownload;
  * This class is started by the main method and provides
  * the central management unit of the groundstation application.
  *
- **/
-class QGCApplication : public QGuiApplication
+ * Needs QApplication base to support QtCharts drawing module and
+ * avoid application crashing on 5.12. Enforce no widget on mobile
+**/
+class QGCApplication :
+      #if defined(__mobile__)
+        public QGuiApplication
+      #else
+        public QApplication
+      #endif
 {
     Q_OBJECT