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;

test/testcustomcursor.c

@@ -223,7 +223,7 @@ static SDL_Cursor *cursors[3 + SDL_SYSTEM_CURSOR_COUNT];
 static SDL_SystemCursor cursor_types[3 + SDL_SYSTEM_CURSOR_COUNT];
 static int num_cursors;
 static int current_cursor;
-static SDL_bool show_cursor;
+static bool show_cursor;
 
 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
 static void
@@ -346,7 +346,7 @@ static void loop(void)
         rect.w = 128.0f;
         rect.h = 128.0f;
         for (y = 0, row = 0; y < window_h; y += (int)rect.h, ++row) {
-            SDL_bool black = ((row % 2) == 0) ? SDL_TRUE : SDL_FALSE;
+            bool black = ((row % 2) == 0) ? true : false;
             for (x = 0; x < window_w; x += (int)rect.w) {
                 rect.x = (float)x;
                 rect.y = (float)y;