privilege seperated pflogd

_pflogd user and group must be created for proper operation.
ok frantzen@ henning@ mcbride@ deraadt@

src/etc/group

@@ -38,6 +38,7 @@ named:*:70:
 proxy:*:71:
 authpf:*:72:
 _syslogd:*:73:
+_pflogd:*:74:
 dialer:*:117:
 nogroup:*:32766:
 nobody:*:32767:

src/etc/master.passwd

@@ -20,4 +20,5 @@ _isakmpd:*:68:68::0:0:isakmpd privsep:/var/empty:/sbin/nologin
 named:*:70:70::0:0:BIND Name Service Daemon:/var/named:/sbin/nologin
 proxy:*:71:71::0:0:Proxy Services:/nonexistent:/sbin/nologin
 _syslogd:*:73:73::0:0:Syslog Daemon:/var/empty:/sbin/nologin
+_pflogd:*:74:74::0:0:pflogd privsep:/var/empty:/sbin/nologin
 nobody:*:32767:32767::0:0:Unprivileged user:/nonexistent:/sbin/nologin