sdl2: Update to version 2.28.1

sdl2: Update to version 2.28.1

- Update from version 2.26.5 to 2.28.1
- Update of rootfile
- Changelog
    2.28.1
	This is a stable bugfix release, with the following changes:
	    Added support for the Nintendo Online Famicom controllers
	    Improved support for third-party Nintendo Switch controllers
	    Fixed setting the player LED on Nintendo Switch controllers
	    Added Linux controller mapping for the Logitech Chillstream
	    Fixed appending to a file greater than 4GB in size on Windows

    2.28.0
	Thanks to all the people who contributed code and feedback, SDL 2.28.0 is now
         available!
	In addition to lots of bug fixes, here are the major changes in this release:
	General:
	    Added SDL_HasWindowSurface() and SDL_DestroyWindowSurface() to switch between
             the window surface and rendering APIs
	    Added a display event SDL_DISPLAYEVENT_MOVED which is sent when the primary
             monitor changes or displays change position relative to each other
	    Added the hint SDL_HINT_ENABLE_SCREEN_KEYBOARD to control whether the
             on-screen keyboard should be shown when text input is active
	With this release, SDL 2.0 is entering maintenance mode. While we will continue
         to support the library and provide stable bug fix updates, the SDL team is
         focusing on SDL 3.0 and all new feature development will be happening there. We
         are simultaneously bringing up sdl2-compat so your existing SDL 2.0 applications
         can run on the SDL 3.0 runtime in the future.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>