Android: Mark "Unknown Android version" string as translateable

Change-Id: I187775878c0fa4341b5eef0bee035fd407fe6aa8
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

src/plugins/android/androidmanager.cpp

@@ -790,7 +790,7 @@ QString AndroidManager::androidNameForApiLevel(int x)
     case 19:
         return QLatin1String("Android 4.4");
     default:
-        return QLatin1String("Unknown Android version.");
+        return tr("Unknown Android version.");
     }
 }