kernel build failure without BPF

in the following kernel configuration (notably without ``device
bfp''), i get the following kernel build error. which is either a bug,
or not; just posting in case it's in someone's interest.

======== build log snippet begins ========
===> pfsync (all)

cc -O2 -fno-strict-aliasing -pipe -march=pentium4 -Werror -D_KERNEL
-DKLD_MODULE -nostdinc  -I/usr/src/sys/modules/pfsync/../../contrib/pf
-DHAVE_KERNEL_OPTION_HEADERS -include
/usr/obj/usr/src/sys/HQ/opt_global.h -I. -I_at_ -I_at_/contrib/altq
-finline-limit=8000 --param inline-unit-growth=100 --param
large-function-growth=1000 -fno-common  -I/usr/obj/usr/src/sys/HQ
-mno-align-long-strings -mpreferred-stack-boundary=2 -mno-sse -mno-mmx
-msoft-float -ffreestanding -fstack-protector -std=iso9899:1999
-fstack-protector -Wall -Wredundant-decls -Wnested-externs
-Wstrict-prototypes  -Wmissing-prototypes -Wpointer-arith -Winline
-Wcast-qual  -Wundef -Wno-pointer-sign -fformat-extensions
-Wmissing-include-dirs -fdiagnostics-show-option -c
/usr/src/sys/modules/pfsync/../../contrib/pf/net/if_pfsync.c

/usr/src/sys/modules/pfsync/../../contrib/pf/net/if_pfsync.c: In
function 'pfsync_sendout':

/usr/src/sys/modules/pfsync/../../contrib/pf/net/if_pfsync.c:2163:
error: 'm' undeclared (first use in this function)

/usr/src/sys/modules/pfsync/../../contrib/pf/net/if_pfsync.c:2163:
error: (Each undeclared identifier is reported only once

/usr/src/sys/modules/pfsync/../../contrib/pf/net/if_pfsync.c:2163:
error: for each function it appears in.)

*** Error code 1



Stop in /usr/src/sys/modules/pfsync.

*** Error code 1

======== build log snippet ends ========
======== kernel configuration file begins ========
cpu		I686_CPU
ident		HQ

#options 	SCHED_ULE		# ULE scheduler
options 	SCHED_4BSD
options 	PREEMPTION		# Enable kernel thread preemption
options 	INET			# InterNETworking
#options 	INET6			# IPv6 communications protocols
options 	SCTP			# Stream Control Transmission Protocol
options 	FFS			# Berkeley Fast Filesystem
options 	SOFTUPDATES		# Enable FFS soft updates support
options 	UFS_ACL			# Support for access control lists
options 	UFS_DIRHASH		# Improve performance on big directories
options 	MD_ROOT			# MD is a potential root device
options 	NFSCL			# New Network Filesystem Client
options 	NFSD			# New Network Filesystem Server
options 	NFSLOCKD		# Network Lock Manager
options 	NFS_ROOT		# NFS usable as /, requires NFSCL
options 	MSDOSFS			# MSDOS Filesystem
options 	CD9660			# ISO 9660 Filesystem
options 	GEOM_LABEL		# Provides labelization
options 	COMPAT_FREEBSD4		# Compatible with FreeBSD4
options 	COMPAT_FREEBSD5		# Compatible with FreeBSD5
options 	COMPAT_FREEBSD6		# Compatible with FreeBSD6
options 	COMPAT_FREEBSD7		# Compatible with FreeBSD7
options 	SCSI_DELAY=1000		# Delay (in ms) before probing SCSI
options 	SYSVSHM			# SYSV-style shared memory
options 	SYSVMSG			# SYSV-style message queues
options 	SYSVSEM			# SYSV-style semaphores
options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
options 	PRINTF_BUFR_SIZE=128	# Prevent printf output being interspersed.
options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
options 	MAC			# TrustedBSD MAC Framework

# To make an SMP kernel, the next two lines are needed
options 	SMP			# Symmetric MultiProcessor Kernel
device		apic			# I/O APIC

# CPU frequency control
device		cpufreq

# Bus support.
device		acpi
device		pci

# ATA controllers
device		ata		# Legacy ATA/SATA controllers
options 	ATA_CAM		# Handle legacy controllers with CAM
options 	ATA_STATIC_ID	# Static device numbering

# ATA/SCSI peripherals
device		scbus		# SCSI bus (required for ATA/SCSI)
device		ch		# SCSI media changers
device		da		# Direct Access (disks)
#device		sa		# Sequential Access (tape etc)
device		cd		# CD
device		pass		# Passthrough device (direct ATA/SCSI access)
device		ses		# SCSI Environmental Services (and SAF-TE)

# atkbdc0 controls both the keyboard and the PS/2 mouse
device		atkbdc		# AT keyboard controller
device		atkbd		# AT keyboard
device		psm		# PS/2 mouse

#device		kbdmux		# keyboard multiplexer

device		vga		# VGA video card driver

# syscons is the default console driver, resembling an SCO console
device		sc

device		agp		# support several AGP chipsets

# Power management support (see NOTES for more options)
#device		apm
# Add suspend/resume support for the i8254.
device		pmtimer

# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device		miibus		# MII bus support
device		sk		# SysKonnect SK-984x & SK-982x gigabit Ethernet

# Pseudo devices.
device		loop		# Network loopback
device		random		# Entropy device
device		ether		# Ethernet support
#device		tun		# Packet tunnel.
device		pty		# BSD-style compatibility pseudo ttys
device		md		# Memory "disks"
device		gif		# IPv6 and IPv4 tunneling
#device		faith		# IPv6-to-IPv4 relaying (translation)
device		firmware	# firmware assist module

# The `bpf' device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
# Note that 'bpf' is required for DHCP.
#device		bpf		# Berkeley packet filter

# USB support
#options 	USB_DEBUG	# enable debug msgs
device		uhci		# UHCI PCI->USB interface
device		ohci		# OHCI PCI->USB interface
device		ehci		# EHCI PCI->USB interface (USB 2.0)
device		usb		# USB Bus (required)
#device		udbp		# USB Double Bulk Pipe devices (needs netgraph)
device		uhid		# "Human Interface Devices"
device		ukbd		# Keyboard
#device		ulpt		# Printer
device		umass		# Disks/Mass storage - Requires scbus and da
device		ums		# Mouse

# Sound support
device		sound		# Generic sound driver (required)
device		snd_es137x	# Ensoniq AudioPCI ES137x

device		drm
device		radeondrm
======== kernel configuration file ends ========