Added missing bullet library for android

Added missing bullet library for android
    src/Android.mk
Fixed broken android caused by updated SDL library

Fixed broken android caused by updated SDL library

These changes are just the updated android SDLActivity.jave fro the SDL repo,
together with library loading as before.

    android/src/org/libsdl/app/SDLActivity.java
Fixed glslangValidator download in init script

Fixed glslangValidator download in init script
    initialize_project.sh