Use SDL_bool instead an int return code in the SDL API

Most SDL functions used to indicate success or failure using an int return code. These functions have been changed to return SDL_bool.

Here is a coccinelle patch to change code that previously compared the return value to 0 and changes it to a boolean test:
@ bool_return_type @
identifier func =~ "^(IMG_SaveAVIF|IMG_SaveAVIF_IO|IMG_SaveJPG|IMG_SaveJPG_IO|IMG_SavePNG|IMG_SavePNG_IO)$"
@@
(
  func(
  ...
  )
- == 0
|
- func(
+ !func(
  ...
  )
- < 0
|
- func(
+ !func(
  ...
  )
- != 0
|
- func(
+ !func(
  ...
  )
- == -1
)

examples/showimage.c

@@ -173,19 +173,19 @@ int main(int argc, char *argv[])
             SDL_Surface *surface = IMG_Load(argv[i]);
             if (surface) {
                 const char *ext = SDL_strrchr(saveFile, '.');
+                SDL_bool saved = SDL_FALSE;
                 if (ext && SDL_strcasecmp(ext, ".avif") == 0) {
-                    result = IMG_SaveAVIF(surface, saveFile, 90);
+                    saved = IMG_SaveAVIF(surface, saveFile, 90);
                 } else if (ext && SDL_strcasecmp(ext, ".bmp") == 0) {
-                    result = SDL_SaveBMP(surface, saveFile);
+                    saved = SDL_SaveBMP(surface, saveFile);
                 } else if (ext && SDL_strcasecmp(ext, ".jpg") == 0) {
-                    result = IMG_SaveJPG(surface, saveFile, 90);
+                    saved = IMG_SaveJPG(surface, saveFile, 90);
                 } else if (ext && SDL_strcasecmp(ext, ".png") == 0) {
-                    result = IMG_SavePNG(surface, saveFile);
+                    saved = IMG_SavePNG(surface, saveFile);
                 } else {
                     SDL_SetError("Unknown save file type");
-                    result = -1;
                 }
-                if (result < 0) {
+                if (!saved) {
                     SDL_Log("Couldn't save %s: %s\n", saveFile, SDL_GetError());
                     result = 3;
                 }