SDL_hidapi.c: change 'use_libusb_whitelist_default' into a macro.

Avoids 'initializer element is not constant' error from older compilers.

src/hidapi/SDL_hidapi.c

@@ -902,9 +902,9 @@ IsInWhitelist(Uint16 vendor, Uint16 product)
 }
 
 #if HAVE_PLATFORM_BACKEND || HAVE_DRIVER_BACKEND
-static const SDL_bool use_libusb_whitelist_default = SDL_TRUE;
+#define use_libusb_whitelist_default SDL_TRUE
 #else
-static const SDL_bool use_libusb_whitelist_default = SDL_FALSE;
+#define use_libusb_whitelist_default SDL_FALSE
 #endif /* HAVE_PLATFORM_BACKEND || HAVE_DRIVER_BACKEND */
 static SDL_bool use_libusb_whitelist = use_libusb_whitelist_default;