Log Message:
Update to 1.2.10.

Package changes:
Merge SDL-arts, SDL-esound, and SDL-nas packages back as options,
all defaulting to on (add "-arts -esound -nas" to PKG_OPTIONS.SDL
to get the previous behaviour of this package). Reason: trying to
get and stay in sync with upstream, who decided not to take back
the relevant changes. Ok jmmv@

Also follow upstream w.r.t. library version numbers; bump
BUILDLINK_API_DEPENDS for that (no real reason to diverge here).

Most patches have been integrated upstream.

Changes in 1.2.10:

1.2.10:
	If SDL_OpenAudio() is passed zero for the desired format
	fields, the following environment variables will be used
	to fill them in:
		SDL_AUDIO_FREQUENCY
		SDL_AUDIO_FORMAT
		SDL_AUDIO_CHANNELS
		SDL_AUDIO_SAMPLES
	If an environment variable is not specified, it will be set
	to a reasonable default value.

	Added support for the SDL_VIDEO_FULLSCREEN_HEAD environment
	variable, currently supported on X11 Xinerama configurations.

	Added SDL_GL_SWAP_CONTROL to wait for vsync in OpenGL applications.

	Added SDL_GL_ACCELERATED_VISUAL to guarantee hardware acceleration.

	Added current_w and current_h to the SDL_VideoInfo structure,
	which is set to the desktop resolution during video intialization,
	and then set to the current resolution when a video mode is set.

	SDL_SetVideoMode() now accepts 0 for width or height and will use
	the current video mode (or the desktop mode if no mode has been set.)

	Added SDL_GetKeyRepeat()

	Added SDL_config.h, with defaults for various build environments.