Comment 6 for bug 1774903

Reviewed: https://review.opencontrail.org/44916
Committed: http://github.com/Juniper/contrail-vrouter/commit/aeace07394c03a48e83f6dd9c63aa17660b4bf33
Submitter: Zuul v3 CI (<email address hidden>)
Branch: R5.0

commit aeace07394c03a48e83f6dd9c63aa17660b4bf33
Author: Yi Yang <email address hidden>
Date: Mon Jun 4 14:04:09 2018 +0800

Fix a segment fault error for DPDK 17.02

I found a segment fault error when I use DPDK 17.02 branch, here is
segment fault information:

Program terminated with signal SIGSEGV, Segmentation fault.
702 __builtin_ia32_storedqu ((char *)__P, (__v16qi)__B);
(gdb) bt
at build/production/vrouter/dpdk/x86_64-native-linuxapp-gcc/include/rte_memcpy.h:820
at build/production/vrouter/dpdk/x86_64-native-linuxapp-gcc/include/rte_memcpy.h:896
at vrouter/dpdk/vr_dpdk_host.c:793
at vrouter/dp-core/vr_proto_ip.c:373
(gdb)

We encountered it in DPDK 17.11 branch, the issue is rte_mbuf can't be freed
if it is copied or cloned from another rtm_mbuf with IND_ATTACHED_MBUF flag,
it will result in very weird issues.

Change-Id: Iae6d229488225a97ef2f96c52db1dbcaaa32b51a
Closes-Bug: #1774903
Signed-off-by: Yi Yang <email address hidden>
(cherry picked from commit e866729fec6315bb4d62ccc2c3e891f4566644fa)