Merge pull request #21 from suve/add-SDL_tray

Add SDL_tray.inc (v3.2.12)

Author: Free-Pascal-meets-SDL-Website

units/SDL3.pas

@@ -125,6 +125,7 @@ interface
 {$I SDL_thread.inc}                       // 3.2.0
 {$I SDL_process.inc}                      // 3.2.0
 {$I SDL_storage.inc}                      // 3.2.0
+{$I SDL_tray.inc}                         // 3.2.12