Turn DEBUGCONSOLE on by default

This directive is to control the behavior of (debug_printf),
which is used to print some message to STDERR. We turn this on
by default, to get some debug/error message just-in-time. For
example, if we can not find log file, we write to STDERR
Option -c accepts real path of config. file

* Old: $listserver-conf} + ${value of -c}
* New: Only join path if user value is not a real path

See notes in source code for more details