title: Gradle sync failed, NDK not configured, download it with SDK manager
body: <p>I am completely new to Android development and just installed Android Studio. I'm doing a very basic HelloGL2 exercise, and I opened up the HelloGL2.iml file. I tried running it, but it said that the gradle project sync failed and that the NDK is not configured. In the simplest terms (to a complete beginner in Android), how do I fix this?</p>