M1: compat layer + pf.ko skeleton builds against Linux 7.3.4

- pfk.h: BSD types/ioctl encoding (OpenBSD bit layout), locks (NET_LOCK=rwsem),
  pools, timeouts, mbuf shim over sk_buff, ifnet registry, toeplitz/siphash
- pfk_mod/pfk_hooks: misc /dev/pf (0600), IPv4 netfilter hook skeleton,
  DIOCGETSTATUS answered (M1 skeleton; engine ioctls land with pf_ioctl.c)
- vendorize/stage-port scripts: deterministic upstream staging with seds
  (struct renames, IFF_*->PFIFF_*, sa_len drops) logged to docs/porting-notes
- fixes: modules_prepare+Module.symvers for out-of-tree builds

module/include/compat/net/if_pflog.h

@@ -0,0 +1,72 @@
+/* $OpenBSD: if_pflog.h,v 1.29 2021/01/13 09:13:30 mvs Exp $ */
+/*
+ * Copyright 2001 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _NET_IF_PFLOG_H_
+#define _NET_IF_PFLOG_H_
+
+#include <sys/queue.h>
+#include <net/pfvar.h>
+
+#define PFLOG_RULESET_NAME_SIZE	16
+
+struct pfloghdr {
+	u_int8_t	length;
+	sa_family_t	af;
+	u_int8_t	action;
+	u_int8_t	reason;
+	char		ifname[IFNAMSIZ];
+	char		ruleset[PFLOG_RULESET_NAME_SIZE];
+	u_int32_t	rulenr;
+	u_int32_t	subrulenr;
+	uid_t		uid;
+	pid_t		pid;
+	uid_t		rule_uid;
+	pid_t		rule_pid;
+	u_int8_t	dir;
+	u_int8_t	rewritten;
+	sa_family_t	naf;
+	u_int8_t	pad[1];
+	struct pf_addr	saddr;
+	struct pf_addr	daddr;
+	u_int16_t	sport;
+	u_int16_t	dport;
+};
+
+#define PFLOG_HDRLEN		sizeof(struct pfloghdr)
+/* used to be minus pad, also used as a signature */
+#define PFLOG_REAL_HDRLEN	PFLOG_HDRLEN
+#define PFLOG_OLD_HDRLEN	offsetof(struct pfloghdr, pad)
+
+#ifdef _KERNEL
+
+struct pflog_softc {
+	LIST_ENTRY(pflog_softc)		sc_entry;
+	struct ifnet			sc_if;		/* the interface */
+	int				sc_unit;
+};
+
+#endif /* _KERNEL */
+#endif /* _NET_IF_PFLOG_H_ */