How to make arm64-v8a show up in Build Variant in Android Studio?

#1

I downloaded the arm64 libs from http://ci.openframeworks.cc/libs/ and replaced the all the libs with the current ones in OF/libs.

And then I opened an OF project in Android Studio but I cannot see arm64-v8a option form Build Variant section.

How to make arm64-v8a show up in the Build Variant so I can build the project using it?