examples/ipv4_multicast: fix leak of cloned packets

examples/ipv4_multicast: fix leak of cloned packets

The ipv4_multicast sample application was dropping packets
when using mbuf clone. When creating an L2 header and copying
metadata from the source packet, the ol_flags were also copied
along with all the other metadata. Because the cloned packet
had IND_ATTACHED_MBUF flag set in its ol_flags,
this caused the packets to never be freed when using rte_pktmbuf_free.
Since copying ol_flags from the cloned packet is
not necessary in the first place, just don't do it.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org
Reported-by: Dong Wang <dong1.wang@intel.com>
Signed-off-by: Herakliusz Lipiec <herakliusz.lipiec@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Dong Wang <dong1.wang@intel.com>