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);

libobs/util/c99defs.h

@@ -24,12 +24,10 @@
 #define UNUSED_PARAMETER(param) (void)param
 
 #ifdef _MSC_VER
-#define DEPRECATED_START __declspec(deprecated)
-#define DEPRECATED_END
+#define DEPRECATED __declspec(deprecated)
 #define FORCE_INLINE __forceinline
 #else
-#define DEPRECATED_START
-#define DEPRECATED_END __attribute__ ((deprecated))
+#define DEPRECATED __attribute__ ((deprecated))
 #define FORCE_INLINE inline __attribute__((always_inline))
 #endif