Add sdl3_main.odin

vendor/sdl3/sdl3_main.odin

@@ -0,0 +1,21 @@
+package sdl3
+
+import "core:c"
+
+typedef int (SDLCALL *SDL_main_func)(int argc, char *argv[]);
+
+@(default_calling_convention="c", link_prefix="SDL_")
+foreign lib {
+	AppInit               :: proc(appstate: ^rawptr, argc: c.int, argv: [^]cstring) -> AppResult ---
+	AppIterate            :: proc(appstate: rawptr) -> AppResult ---
+	AppEvent              :: proc(appstate: rawptr, event: ^Event) -> AppResult ---
+	AppQuit               :: proc(appstate: rawptr, SDL_AppResult result) ---
+	main                  :: proc(argc: c.int, argv: [^]cstring) -> c.int ---
+	SetMainReady          :: proc() ---
+	RunApp                :: proc(argc: c.int, argv: [^]cstring, mainFunction: main_func, reserved: rawptr) -> c,int ---
+	EnterAppMainCallbacks :: proc(argc: c.int, argv: [^]cstring, appinit: AppInit_func, appiter: AppIterate_func, appevent: AppEvent_func, appquit: AppQuit_func) -> c.int ---
+	RegisterApp           :: proc(name: cstring, Uint32 style, hInst: rawptr) -> bool ---
+	UnregisterApp         :: proc() ---
+	GDKSuspendComplete    :: proc() ---
+
+}