SDL_platform.h: define TARGET_OS_SIMULATOR as 0 if not already defined. c.f.: https://github.com/libsdl-org/SDL/issues/4475
diff --git a/include/SDL_platform.h b/include/SDL_platform.h
index b4e7b7f..1516da3 100644
--- a/include/SDL_platform.h
+++ b/include/SDL_platform.h
@@ -87,6 +87,9 @@
#ifndef TARGET_OS_TV
#define TARGET_OS_TV 0
#endif
+#ifndef TARGET_OS_SIMULATOR
+#define TARGET_OS_SIMULATOR 0
+#endif
#if TARGET_OS_TV
#undef __TVOS__