starter: Ensure the daemon executable exists when starting up

The only purpose of starter is to control the IKE daemon, so we
terminate it if the daemon executable is not found (e.g. because
DAEMON_NAME is incorrect).

This removes the charonstart setting (it was not actually configurable
anymore).

src/starter/starter.c

@@ -517,6 +517,13 @@ int main (int argc, char **argv)
 		exit(status);
 	}
 
+	if (stat(cmd, &stb) != 0)
+	{
+		DBG1(DBG_APP, "IKE daemon '%s' not found", cmd);
+		cleanup();
+		exit(LSB_RC_FAILURE);
+	}
+
 	DBG1(DBG_APP, "Starting %sSwan "VERSION" IPsec [starter]...",
 		lib->settings->get_bool(lib->settings,
 			"charon.i_dont_care_about_security_and_use_aggressive_mode_psk",
@@ -836,7 +843,7 @@ int main (int argc, char **argv)
 		 */
 		if (_action_ & FLAG_ACTION_START_CHARON)
 		{
-			if (cfg->setup.charonstart && !starter_charon_pid())
+			if (!starter_charon_pid())
 			{
 				DBG2(DBG_APP, "Attempting to start %s...", daemon_name);
 				if (starter_start_charon(cfg, no_fork, attach_gdb))