Mark Callow
README-android says to copy or link the SDL source tree to the jni folder in your Android project. It is not desirable to have to compile SDL with every application; furthermore the Android NDK has support for prebuilt libraries.
Attached is script (to be put in build-scripts) that builds the Android version of the libraries. The script builds both the existing SDL2 module and a new SDL2_main module. This is a static library containing the code from src/main/android/SDL_android_main.c. Also attached is a patch for Android.mk adding this module.
Note that when building an application's native .so using this prebuilt libSDL2main, you must use a link option, such as --whole-archive, that forces inclusion of the code in the .so because the functions in SDL_android_main are called only from Java.
Sam Lantinga