include/starpu_util.h: deactivate deprecated warning when using deprecated API (there is already a API warning being displayed)

include/starpu_util.h

@@ -76,7 +76,7 @@ extern "C"
 #  define STARPU_ATTRIBUTE_INTERNAL
 #endif
 
-#if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)) && !defined(BUILDING_STARPU)
+#if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)) && !defined(BUILDING_STARPU) && !defined(STARPU_USE_DEPRECATED_API)
 #define STARPU_DEPRECATED  __attribute__((__deprecated__))
 #else
 #define STARPU_DEPRECATED