defect 3789: fixed the issue that xcatdebug command kill the xcatd ssl listening process. The fix is that just remove the handling debug message from plugin modules since xcatd loads plugin modules for each command run, don't need xcatdebug for plugin any more.

xCAT-server/sbin/xcatd

@@ -2177,7 +2177,7 @@ sub enable_callingtrace{
   my @xcatdfuncs = (); # function list that will be enabled for xcatd
 
   # call the subroutine scan_plugins to fill the symbol table
-  scan_plugins();
+  #scan_plugins();
 
   # Backup the trace log
   my ($sec,$min,$hour,$mday,$mon,$year) = localtime();