added check to avoid failing 'ip6_getpktaddrs()' in mip6_bc_encapcheck on NetBSD(OpenBSD).
added check to avoid failing 'ip6_getpktaddrs()' in mip6_bc_encapcheck
on NetBSD(OpenBSD).

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame