[Core] Fix possible leak of the subclass variable in CUSTOM_HASH'es switch_event_reserve_subclass_detailed().

src/switch_utils.c

@@ -71,6 +71,11 @@ struct switch_network_list {
 	char *name;
 };
 
+SWITCH_DECLARE(void *) switch_calloc(size_t nmemb, size_t size)
+{
+	return calloc(nmemb, size);
+}
+
 #ifndef WIN32
 SWITCH_DECLARE(int) switch_inet_pton(int af, const char *src, void *dst)
 {