Medium: Xinetd: refine exit codes when xinetd is stopped

Spotted by @bubble666:

https://github.com/ClusterLabs/resource-agents/commit/e9c03c15bdfa49a6bfce784ab922dd0ece546561#commitcomment-4983265
Merge pull request #480 from dmuhamedagic/xinetd-err_installed

Medium: Xinetd: refine exit codes when xinetd is stopped