Fixed minor issues found with static code analyzis (Clang).

src/core/auth.c

@@ -86,7 +86,8 @@ static int check_cmd_user(const char* cmd, int status, struct linked_list* list,
 		}
 
 		strncpy(info->nickname, data, MAX_NICK_LEN);
-		strncpy(info->password, data_extra, MAX_PASS_LEN);
+		if (data_extra)
+			strncpy(info->password, data_extra, MAX_PASS_LEN);
 		info->credentials = status;
 		list_append(list, info);
 		LOG_DEBUG("ACL: Added user '%s' (%s)", info->nickname, auth_cred_to_string(info->credentials));