Removed SDL_bool in favor of plain bool

We require stdbool.h in the build environment, so we might as well use the plain bool type.

If your environment doesn't have stdbool.h, this simple replacement will suffice:
typedef signed char bool;

docs/README-wayland.md

@@ -61,7 +61,7 @@ having SDL handle input and rendering, it needs to create a custom, roleless sur
 toplevel window.
 
 This is done by using `SDL_CreateWindowWithProperties()` and setting the
-`SDL_PROP_WINDOW_CREATE_WAYLAND_SURFACE_ROLE_CUSTOM_BOOLEAN` property to `SDL_TRUE`. Once the window has been
+`SDL_PROP_WINDOW_CREATE_WAYLAND_SURFACE_ROLE_CUSTOM_BOOLEAN` property to `true`. Once the window has been
 successfully created, the `wl_display` and `wl_surface` objects can then be retrieved from the
 `SDL_PROP_WINDOW_WAYLAND_DISPLAY_POINTER` and `SDL_PROP_WINDOW_WAYLAND_SURFACE_POINTER` properties respectively.
 
@@ -69,10 +69,10 @@ Surfaces don't receive any size change notifications, so if an application chang
 that the surface size has changed by calling SDL_SetWindowSize() with the new dimensions.
 
 Custom surfaces will automatically handle scaling internally if the window was created with the
-`SDL_PROP_WINDOW_CREATE_HIGH_PIXEL_DENSITY_BOOLEAN` property set to `SDL_TRUE`. In this case, applications should
+`SDL_PROP_WINDOW_CREATE_HIGH_PIXEL_DENSITY_BOOLEAN` property set to `true`. In this case, applications should
 not manually attach viewports or change the surface scale value, as SDL will handle this internally. Calls
 to `SDL_SetWindowSize()` should use the logical size of the window, and `SDL_GetWindowSizeInPixels()` should be used to
-query the size of the backbuffer surface in pixels. If this property is not set or is `SDL_FALSE`, applications can
+query the size of the backbuffer surface in pixels. If this property is not set or is `false`, applications can
 attach their own viewports or change the surface scale manually, and the SDL backend will not interfere or change any
 values internally. In this case, calls to `SDL_SetWindowSize()` should pass the requested surface size in pixels, not
 the logical window size, as no scaling calculations will be done internally.
@@ -101,7 +101,7 @@ SDL receives no notification regarding size changes on external surfaces or topl
 needs to be resized, SDL must be informed by calling SDL_SetWindowSize() with the new dimensions.
 
 If desired, SDL can automatically handle the scaling for the surface by setting the
-`SDL_PROP_WINDOW_CREATE_HIGH_PIXEL_DENSITY_BOOLEAN` property to `SDL_TRUE`, however, if the surface being imported
+`SDL_PROP_WINDOW_CREATE_HIGH_PIXEL_DENSITY_BOOLEAN` property to `true`, however, if the surface being imported
 already has, or will have, a viewport/fractional scale manager attached to it by the application or an external toolkit,
 a protocol violation will result. Avoid setting this property if importing surfaces from toolkits such as Qt or GTK.
 
@@ -176,7 +176,7 @@ int main(int argc, char *argv[])
      */
     props = SDL_CreateProperties();
     SDL_SetPointerProperty(props, SDL_PROP_WINDOW_CREATE_WAYLAND_WL_SURFACE_POINTER, surface);
-    SDL_SetBooleanProperty(props, SDL_PROP_WINDOW_CREATE_OPENGL_BOOLEAN, SDL_TRUE);
+    SDL_SetBooleanProperty(props, SDL_PROP_WINDOW_CREATE_OPENGL_BOOLEAN, true);
     SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_WIDTH_NUMBER, 640);
     SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_HEIGHT_NUMBER, 480);
     sdlWindow = SDL_CreateWindowWithProperties(props);