new talloc stuff

[tridge at samba.org]

Volker,

 > And these exceptions are probably rare enough that you do not want to put a
 > mutex of any kind around the talloc operations....

The exceptions need to be fixed :)

The main exception I can think of is the global context associated
with loadparm. See lp_talloc in loadparm.c. The loadparm code needs a
major revamp at some stage, and certainly I would rather fix loadparm
than add mutexes in talloc.c.

Cheers, Tridge