rip6_output WITNESS warning

Hi rwatson.

	I contacted WITNESS warning on boot(newest current) in my
	SMP machine(PentiumIII x2).

Mounting root from ufs:/dev/ad0s1a
Sleeping in "rip6_output" with the following non-sleepable locks held:
exclusive sleep mutex inp (raw6inp) r = 0 (0xc3181090) locked _at_ /devel/src/sys/netinet6/raw_ip6.c:346
exclusive sleep mutex rip r = 0 (0xc08183cc) locked _at_ /devel/src/sys/netinet6/raw_ip6.c:744
KDB: stack backtrace:
kdb_backtrace(c0814d74,e3d42aa8,1,1,2) at kdb_backtrace+0x2e
witness_warn(5,0,c0743b3f,c071c348,0) at witness_warn+0x1d3
rip6_output(c312d800,c307e8a4,e3d42b84,c312d900,1c1c) at rip6_output+0x19b
rip6_send(c307e8a4,0,c312d800,c317fc00,c312d900) at rip6_send+0x146
sosend(c307e8a4,c317fc00,e3d42c44,c312d800,c312d900) at sosend+0x87d
kern_sendit(c30159a0,3,e3d42cbc,0,c312d900) at kern_sendit+0x13c
sendit(c30159a0,3,e3d42cbc,0,c2e00d40) at sendit+0x19b
sendmsg(c30159a0,e3d42d14,c,431,3) at sendmsg+0x82
syscall(2f,2f,2f,4,1) at syscall+0x2a0
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (28, FreeBSD ELF32, sendmsg), eip = 0x680d63ef, esp = 0xbfbfed9c, ebp = 0xbfbfede8 ---
sym0:0:control msgout: 80 20 17 d.

FreeBSD/i386 (nadesico.ninth-nine.com) (dcons)