If a debug class was explicitly set to zero the debug system would not
recognise it as there was no distinction made between zeroing a debug
class and just not setting it to anything. I've added a
debuglevel_isset array in parallel with the debuglevel_class array to
fix this.
Added a couple of new debug classes which I might start filling out
to get smb, rpc header and rpc marshall/unmarshalling debugs tidied
up.
Fixed a bunch of cut&paste bugs in include/debug.h
Modified smbcontrol and the messaging system debug handler to like the
debuglevel_isset stuff.
(This used to be commit
391e7caf76cbc22021629ef0ec5e0c32806edfd7)