add missing RCSIDs

(copyrights could be added too - that's up to christos@)

libexec/ftpd/pfilter.c

@@ -1,3 +1,5 @@
+/*	$NetBSD: pfilter.c,v 1.4 2020/07/04 05:18:37 lukem Exp $	*/
+
 #include <stdio.h>
 #include <unistd.h>
 #include <blocklist.h>

libexec/ftpd/pfilter.h

@@ -1,2 +1,4 @@
+/*	$NetBSD: pfilter.h,v 1.2 2020/07/04 05:18:37 lukem Exp $	*/
+
 void pfilter_open(void);
 void pfilter_notify(int, const char *);