memory_utils: adapt to new pointer error macros

src/lxc/memory_utils.h

@@ -52,8 +52,10 @@ define_cleanup_function(DIR *, closedir);
 
 #define free_disarm(ptr)                    \
 	({                                  \
+		if (!IS_ERR_OR_NULL(ptr)) { \
 			free(ptr);          \
 			ptr = NULL;         \
+		}                           \
 	})
 
 static inline void free_disarm_function(void *ptr)
@@ -64,7 +66,7 @@ static inline void free_disarm_function(void *ptr)
 
 static inline void free_string_list(char **list)
 {
-	if (list) {
+	if (list && !IS_ERR(list)) {
 		for (int i = 0; list[i]; i++)
 			free(list[i]);
 		free_disarm(list);