Never select the PCB that has INP_IPV6 flag and is bound to :: if we have another PCB which is bound to 0.0.0.0.  If a PCB has the INP_IPV6 flag, then we set its cost higher than IPv4 only PCBs.
Never select the PCB that has INP_IPV6 flag and is bound to :: if
we have another PCB which is bound to 0.0.0.0.  If a PCB has the
INP_IPV6 flag, then we set its cost higher than IPv4 only PCBs.

Submitted by:	Keiichi SHIMA <keiichi__at__iijlab.net>
Obtained from:	KAME
MFC after:	1 week

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