allow MacOS build without SDL_FILE

CMakeLists.txt

@@ -1838,8 +1838,6 @@ elseif(APPLE)
     # !!! FIXME: modern CMake doesn't need "LANGUAGE C" for Objective-C.
     set_source_files_properties(${EXTRA_SOURCES} PROPERTIES LANGUAGE C)
     set(HAVE_SDL_FILE TRUE)
-  else()
-    message_error("SDL_FILE must be enabled to build on MacOS X")
   endif()
 
   if(IOS OR TVOS)

src/file/SDL_rwops.c

@@ -833,7 +833,7 @@ SDL_RWFromFile(const char *file, const char *mode)
     rwops->type = SDL_RWOPS_VITAFILE;
 #elif HAVE_STDIO_H
     {
-        #ifdef __APPLE__
+        #if __APPLE__ && !SDL_FILE_DISABLED // TODO: add dummy?
         FILE *fp = SDL_OpenFPFromBundleOrFallback(file, mode);
         #elif __WINRT__
         FILE *fp = NULL;