Update SDL2 on Android

[rollerozxa]

Currently the Android version uses the vendored version of SDL2 available in the source tree. This SDL2 seems to be some super ancient beta version from 2012(?) predating even a stable release of SDL2. It also causes a segfault in newer versions of the Android NDK trying to compile the game.

I tried to update it to the latest but ran into several issues, TMS includes internal SDL2 headers that have changed significantly since the SDL2 2012 beta, and the Java code needs a lot of changes to work with newer versions of the SDL2 Android Java wrapper code.

For anyone interested, here's the buildscript I used for building newer SDL2 libraries for Android: https://gist.github.com/rollerozxa/9ff0eaec940cdfd6a23859ef2f26b5c8