Squashed 'external/SDL/' content from commit 716c767b7

git-subtree-dir: external/SDL
git-subtree-split: 716c767b7e7099fb0e2fda9db59227a7e1d1d8a4

cmake/test/sdltest.c

@@ -0,0 +1,24 @@
+#define SDL_MAIN_USE_CALLBACKS
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <SDL3/SDL_test.h>
+
+SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
+{
+    return SDL_APP_SUCCESS;
+}
+
+SDL_AppResult SDL_AppIterate(void *appstate)
+{
+    return SDL_APP_SUCCESS;
+}
+
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+    SDLTest_CommonState state;
+    SDLTest_CommonDefaultArgs(&state, argc, argv);
+    return SDL_APP_SUCCESS;
+}
+
+void SDL_AppQuit(void *appstate, SDL_AppResult result) {
+}