make IPv4 AH work in m_pulldown case.  some of upper-layers (specifically, ICMPv4) is not correctly written to handle extension headers. we need to: - strip off AH - change all ICMPv4 code to fix it.  we picked the former way.
make IPv4 AH work in m_pulldown case.  some of upper-layers (specifically,
ICMPv4) is not correctly written to handle extension headers.
we need to:
- strip off AH
- change all ICMPv4 code
to fix it.  we picked the former way.

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