Remove dependency to the NDK.

[mateli]

Let's study what the NDK actually do and replace it with lean open source code that produce the same or better binaries.

Or perhaps make glue code that is built with the NDK but removes the need of using the NDK for the actual application.

[cnlohr]

I am happy to link/work with/etc... this. But, considering it's really hard to get the compiler without some of the android studio components, it just doesn't seem appealing to me to spend all the extra effort to make that worthwhile.

That said, if you get something that works, I'm very interested.