lib/util: new merged debug system

lib/util: new merged debug system

This is the s3 debug system, with a number of changes to tidy it up
for common use.  The debug class system is simplified by the removal of the
ISSET table, the system no longer attempts to cope with assignment of
DEBUGLEVEL, and the full class table is always available (rather than
just DEBUGLEVEL_CLASS[DBCG_ALL]) from startup.  It is also no longer
confusingly described as a hack, but as the initial table.

Autobuild-User: Andrew Bartlett <abartlet@samba.org>
Autobuild-Date: Tue Mar  1 04:32:12 CET 2011 on sn-devel-104