In case of IPsec he have to do delayed checksum calculations before adding any extension header, or rather before calling into IPsec processing as we may send the packet and not return to IPv6 output processing here.
In case of IPsec he have to do delayed checksum calculations before
adding any extension header, or rather before calling into IPsec
processing as we may send the packet and not return to IPv6 output
processing here.

PR:		kern/170116
MFC After:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase