Handle allocation failures in security code

Note that such errors are generally going to be fatal

sway/commands.c

@@ -575,6 +575,9 @@ struct cmd_results *config_commands_command(char *exec) {
 	}
 	if (!policy) {
 		policy = alloc_command_policy(cmd);
+		if (!policy) {
+			sway_abort("Unable to allocate security policy");
+		}
 		list_add(config->command_policies, policy);
 	}
 	policy->context = context;