don't get confused by ifcs created by the clone device but
with no associated device.  also don't corrupt memory
if parsing goes wrong.

example:
minooka; cat /net/ipifc/1/status
device  maxtu 0 sendra 0 recvra 0 mflag 0 oflag 0 maxraint 0 minraint 0 linkmtu 0 reachtime 0 rxmitra 0 ttl 0 routerlt 0 pktin 0 pktout 0 errin 0 errout 0
minooka; ipifc
0:/net/ether0 	00304861c89e	1514
	205.185.197.113/120	205.185.197.0
1:maxtu 	0
0:/net.alt/ether1 	00304861c89f	1514
	65.14.39.134/123	65.14.39.128
	12.51.113.6/123	12.51.113.0
0:/net.10g/ether4 	0060dd4785f5	9000
	205.185.197.114/120	205.185.197.0
minooka; 8.ipifc	# compiled with change.
0:/net/ether0 	00304861c89e	1514
	205.185.197.113/120	205.185.197.0
0:/net.alt/ether1 	00304861c89f	1514
	65.14.39.134/123	65.14.39.128
	12.51.113.6/123	12.51.113.0
0:/net.10g/ether4 	0060dd4785f5	9000
	205.185.197.114/120	205.185.197.0