xcatd failed to start in rhels7.5-snap2 diskless service node

[robin2008]

Workaround (#4929) the MsgUtil.pm first to make sure xcatd will not crash when /dev/log is not ready.
And also move access DB for debug message only to improve the performance.

UT:

[root@sn02 ~]# vi /opt/xcat/lib/perl/xCAT/MsgUtils.pm
[root@sn02 ~]# systemctl start xcatd

[root@sn02 ~]#
[root@sn02 ~]# systemctl status xcatd
● xcatd.service - LSB: xcatd
   Loaded: loaded (/etc/rc.d/init.d/xcatd; bad; vendor preset: disabled)
   Active: active (running) since Tue 2018-03-20 04:43:22 EDT; 6s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 8355 ExecStart=/etc/rc.d/init.d/xcatd start (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/xcatd.service
           ├─8458 xcatd: SSL listener
           ├─8459 xcatd: DB Access
           ├─8460 xcatd: UDP listener
           ├─8461 xcatd: install monitor
           ├─8462 xcatd: Discovery worker
           └─8463 xcatd: Command log writer

Mar 20 04:42:41 sn02.pok.stglabs.ibm.com xcatd[8355]: Subroutine is_valid_config_api redefined at /opt/xcat/lib/perl/xCAT_plugin/openbmc.pm line 4607.
Mar 20 04:42:41 sn02.pok.stglabs.ibm.com xcatd[8355]: Subroutine build_config_api_usage redefined at /opt/xcat/lib/perl/xCAT_plugin/openbmc.pm line 4639.
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: dns server has been enabled on boot.
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: Error: Unable to log to syslog: no connection to syslog available
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: - unix dgram connect: Connection refused
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: - stream can't open /dev/log: No such device or address at /opt/xcat/lib/perl/xCAT/MsgUtils.pm line 479.
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: dns server has been enabled on boot.
Mar 20 04:43:02 sn02.pok.stglabs.ibm.com xcatd[8355]: Job for httpd.service failed because the control process exited with error code. See "systemc...details.
Mar 20 04:43:22 sn02.pok.stglabs.ibm.com xcatd[8355]: [  OK  ]
Mar 20 04:43:22 sn02.pok.stglabs.ibm.com systemd[1]: Started LSB: xcatd.
Hint: Some lines were ellipsized, use -l to show in full.

2, update MsgUtil.pm and run packimage again, then reinstall service node in debugmode, now xcatd can survive when log is not ready.

[xcatbot]

CI CHECK RESULT : > PR FORMAT CORRECT> BUILD SUCCESSFUL > INSTALL XCAT SUCCESSFUL> CODE SYNTAX CORRECT> FAST REGRESSION TEST Successful: Totalcase 215 Pass 215 failed 0

[immarvin]

i am ok to merge this