Android: Fix compilation with Qt 4.

Change-Id: I8f5e310f14159238079f30dded0e5f0814d20990
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/android/androidmanifesteditorwidget.cpp

@@ -875,7 +875,11 @@ int extractVersion(const QString &string)
     int index = string.indexOf(QLatin1Char(':'));
     if (index == -1)
         return 0;
+#if QT_VERSION < 0x050000
+    return string.mid(4, index - 4).toInt();
+#else
     return string.midRef(4, index - 4).toInt();
+#endif
 }
 
 void AndroidManifestEditorWidget::syncToEditor()