render: Updates to format-string versions of SDL_RenderDebugText.

- Removes SDL_RenderDebugTextV
- Changes SDL_RenderDebugTextF to SDL_RenderDebugTextFormat and tweaks it to
  work in a world without SDL_RenderDebugTextV.
- Tweaked rendering position of formatted text in the example program.

examples/renderer/18-debug-text/debug-text.c

@@ -46,6 +46,8 @@ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
 /* This function runs once per frame, and is the heart of the program. */
 SDL_AppResult SDL_AppIterate(void *appstate)
 {
+    const int charsize = SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE;
+
     /* as you can see from this, rendering draws over whatever was drawn before it. */
     SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);  /* black, full alpha */
     SDL_RenderClear(renderer);  /* start with a blank canvas. */
@@ -63,7 +65,7 @@ SDL_AppResult SDL_AppIterate(void *appstate)
     SDL_SetRenderScale(renderer, 1.0f, 1.0f);
     SDL_RenderDebugText(renderer, 64, 350, "This only does ASCII chars. So this laughing emoji won't draw: 🤣");
 
-    SDL_RenderDebugTextF(renderer, 0, 0, "This program has been running for %" SDL_PRIu64 " seconds.", SDL_GetTicks() / 1000);
+    SDL_RenderDebugTextFormat(renderer, (float) ((WINDOW_WIDTH - (charsize * 46)) / 2), 400, "(This program has been running for %" SDL_PRIu64 " seconds.)", SDL_GetTicks() / 1000);
 
     SDL_RenderPresent(renderer);  /* put it all on the screen! */