Allow Android embedders to use SDL without the full video/audio Java
layer by gating subsystem-specific code behind SDL_VIDEO_DISABLED and
SDL_AUDIO_DISABLED preprocessor flags.
This enables applications that only need joystick/gamepad support
(e.g. Qt-based apps like QGroundControl) to build SDL without shipping
stub Java classes for unused subsystems.
Changes:
- Split SDLActivity JNI method table into core (lifecycle, hints,
permissions) and video (surface, input, clipboard, orientation)
- Gate SDLAudioManager and SDLInputConnection JNI registration
- Make checkJNIReady() subsystem-aware: no longer requires
mAudioManagerClass when SDL_AUDIO_DISABLED
- Group method ID resolution by subsystem in nativeSetupJNI()
- Guard all video/audio function implementations and declarations
- Keep display orientation accessors always available (needed by camera)
- Add subsystem-selective SDL.setupJNI(int)/initialize(int) to SDL.java
with backwards-compatible zero-arg overloads
- Guard SDL_VIDEO_DRIVER_ANDROID and related defines in
SDL_build_config_android.h
