umask change in Perl daemon example code

[Florian Weimer <fw@deneb.enyo.de>]

Bug #287119 is caused by the "umask(0);" line in the following code
snippet:

sub become_daemon {
  my $child = fork;
  die "Can't fork: $!" unless defined($child);
  exit(0) if $child;    # parent dies;
  POSIX::setsid();     # become session leader
  open(STDIN,"</dev/null");
  open(STDOUT,">/dev/null");
  open(STDERR, '>&STDOUT');
  chdir '/';           # change working directory
  umask(0);            # forget file mode creation mask
  $ENV{PATH} = '/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin';
  delete @ENV{'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};
  $SIG{CHLD} = \&reap_child;

  # signal handler for child die events
  $SIG{TERM} = $SIG{INT} = \&do_term;
  $SIG{HUP}  = \&do_hup;
}

Apparently, this is part of some standard Perl example for
implementing daemons, which means other packages might be affected as
well.  Symptoms are files which are created world-writable.  For
pperl, I'm going to remove the line and add a regression test.