[CVS] pidfile support

[Henrique de Moraes Holschuh]

I was looking through the new pidfile support stuff, and found a few nits
you guys might want to think about...

1. There is no support for updating the pidfile. Thus, the lock is acquired
only after forking, which means we lost the controlling terminal by the time
we can complain about not being able to acquire a lock, and that we have
already tried to go daemon and thus whatever is trying to start master is
NOT told that we failed.

2. Close on exec is not being set on the pidfile.  Right now, this is not
a bug.  However, should we forget a close(pidfile) anywhere, it could
somehow be the part of a bigger security hole...

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh