s3: increase the log level for missing PIDs on SIGCHLD

s3: increase the log level for missing PIDs on SIGCHLD

Since the fix for bso#7836, the parent smbd is responsible for
maintaining an up-to-date printcap cache. It does this by forking a
child process to asynchronously fetch printcap data from CUPS.

When the child process exits after fetching all printcap data, the
parent smbd is sent SIGCHLD. This triggers smbd_sig_chld_handler() which
looks for the exited process PID on a "children" list.
Child smbd process PIDs are added to the "children" list to ensure
cleanup on unclean shutdown and log level change notification messages.

Printcap update process PIDs are not added to the list as they do not
maintain any state that requires cleanup, nor do they wait on tevent for
messages.

Autobuild-User: Volker Lendecke <vlendec@samba.org>
Autobuild-Date: Thu Feb 17 11:11:45 CET 2011 on sn-devel-104
(cherry picked from commit 9c12232f1ae36e00d04114ad73edd8ba3c2c6a5c)

Fix bug #8269 (smbd spams log with "Could not find child X -- ignoring"
messages).