Updated check for stdbool.h

If you're building in a C99 or newer environment, we'll automatically include stdbool.h.

If you're building in a C89 or C90 environment, we'll assume that stdbool.h isn't available and define bool as an unsigned char. If you have a working stdbool.h and want SDL to use it, you can either include stdbool.h before SDL headers, or define SDL_INCLUDE_STDBOOL_H in your project.

Closes https://github.com/libsdl-org/SDL/pull/10980

src/joystick/gdk/SDL_gameinputjoystick.c

@@ -25,7 +25,6 @@
 #include "../SDL_sysjoystick.h"
 #include "../usb_ids.h"
 
-#include <stdbool.h>
 #define COBJMACROS
 #include <gameinput.h>