sdl2: Update to version 2.0.22

sdl2: Update to version 2.0.22

- Update from version 2.0.20 to 2.0.22
- Update of rootfile
- Changelog
   2.0.22:
     General:
	* Added SDL_RenderGetWindow() to get the window associated with a renderer
	* Added floating point rectangle functions:
	    * SDL_PointInFRect()
	    * SDL_FRectEmpty()
	    * SDL_FRectEquals()
	    * SDL_FRectEqualsEpsilon()
	    * SDL_HasIntersectionF()
	    * SDL_IntersectFRect()
	    * SDL_UnionFRect()
	    * SDL_EncloseFPoints()
	    * SDL_IntersectFRectAndLine()
	* Added SDL_IsTextInputShown() which returns whether the IME window is currently
          shown
	* Added SDL_ClearComposition() to dismiss the composition window without disabling
          IME input
	* Added SDL_TEXTEDITING_EXT event for handling long composition text, and a hint
          SDL_HINT_IME_SUPPORT_EXTENDED_TEXT to enable it
	* Added the hint SDL_HINT_MOUSE_RELATIVE_MODE_CENTER to control whether the mouse
          should be constrained to the whole window or the center of the window when
          relative mode is enabled
	* The mouse is now automatically captured when mouse buttons are pressed, and the
          hint SDL_HINT_MOUSE_AUTO_CAPTURE allows you to control this behavior
	* Added the hint SDL_HINT_VIDEO_FOREIGN_WINDOW_OPENGL to let SDL know that a
          foreign window will be used with OpenGL
	* Added the hint SDL_HINT_VIDEO_FOREIGN_WINDOW_VULKAN to let SDL know that a
          foreign window will be used with Vulkan
	* Added the hint SDL_HINT_QUIT_ON_LAST_WINDOW_CLOSE to specify whether an
          SDL_QUIT event will be delivered when the last application window is closed
	* Added the hint SDL_HINT_JOYSTICK_ROG_CHAKRAM to control whether ROG Chakram
          mice show up as joysticks
     Windows:
	* Added support for SDL_BLENDOPERATION_MINIMUM and SDL_BLENDOPERATION_MAXIMUM to
          the D3D9 renderer
     Linux:
	* Compiling with Wayland support requires libwayland-client version 1.18.0 or later
	* Added the hint SDL_HINT_X11_WINDOW_TYPE to specify the _NET_WM_WINDOW_TYPE of
          SDL windows
	* Added the hint SDL_HINT_VIDEO_WAYLAND_PREFER_LIBDECOR to allow using libdecor
          with compositors that support xdg-decoration
     Android:
	* Added SDL_AndroidSendMessage() to send a custom command to the SDL java activity

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>