Update default script for DHCPD

DHCP Server V3.0.5 running on CentOS 5.8 does not output trailing dot
after reverse DNS zone name. As such,
/usr/share/logwatch/scripts/services/dhcpd needs to be amended:

   } elsif ($line =~ s/^added reverse map from
([\d]+).([\d]+).([\d]+).([\d]+).in-addr.arpa to
([a-zA-Z\d._-]+)\s*$/Add reverse $4.$3.$2.$1 -> $5/) {
      if ($Detail >= 7) {
         $data{'DNS Mappings'}{$line}++;
      }
   } elsif ($line =~ s/^removed reverse map on
([\d]+).([\d]+).([\d]+).([\d]+).in-addr.arpa\s*$/Remove reverse
$4.$3.$2.$1/) {
      if ($Detail >= 7) {
         $data{'DNS Mappings'}{$line}++;

In above, '.in-addr.arpa.' is replaced with '.in-addr.arpa' (last dot removed).

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