Move OpenGL detection before first QApplication* constructor

I don't trust that QCoreApplication really does not touch these global
ctors which create some GL state.

src/main.cpp

@@ -126,6 +126,7 @@ int main(int argc, char *argv[])
 #endif
 
     preinitQt();
+    detectOpenGLEarly();
 
     QStringList arguments;
     for (int i = 0; i < argc; i++)
@@ -157,8 +158,6 @@ int main(int argc, char *argv[])
     else
       qputenv("QT_SCALE_FACTOR", scale.toUtf8());
 
-    detectOpenGLEarly();
-
     QApplication app(argc, newArgv);
     app.setWindowIcon(QIcon(":/images/icon.png"));