libobs: Fix deprecated macro

There's no need to have two separate macros to declare something as
deprecated.

libobs/obs.h

@@ -533,8 +533,8 @@ enum obs_base_effect {
 EXPORT gs_effect_t *obs_get_base_effect(enum obs_base_effect effect);
 
 /* DEPRECATED: gets texture_rect default effect */
-DEPRECATED_START EXPORT gs_effect_t *obs_get_default_rect_effect(void)
-	DEPRECATED_END;
+DEPRECATED
+EXPORT gs_effect_t *obs_get_default_rect_effect(void);
 
 /** Returns the primary obs signal handler */
 EXPORT signal_handler_t *obs_get_signal_handler(void);