Problem with recent patch to update.c

[David Swasey <swasey@cs.cmu.edu>]

There is a minor problem with Dave's recent patch to update.c.  On redhat
linux 4.2, SA_NOCLDWAIT is not defined and the struct sigaction field
he names sa_sigaction is called sa_restorer.

I can't say whether the fix is even needed on linux.  That is, I don't
know whether or not update leaves zombies laying around.  But from the
linux sigaction man page:

>Setting  SIGCHLD  to SIG_IGN provides automatic reaping of
>child processes.

I can also report that there have been no netrek-related zombies on
pickled.

-dave