Specify the XCB library to load for the X11 driver.
Defined in <SDL3/SDL_hints.h>
#define SDL_HINT_X11_XCB_LIBRARY "SDL_X11_XCB_LIBRARY"
The default is platform-specific, often "libX11-xcb.so.1".
This hint should be set before initializing the video subsystem.
This hint is available since SDL 3.0.0.