examples/ipsec-secgw: fix over MTU packet crash
examples/ipsec-secgw: fix over MTU packet crash

When sending an encrypted packet which size after encapsulation exceeds
MTU, ipsec-secgw application tries to fragment it. If --reassemble
option has not been set it results with a segmantation fault, because
fragmentation buckets have not been initialized.

Fix crashing by adding extra check if --ressemble option has not been
set and packet exceeds MTU after encapsulation - drop it.

Fixes: b01d1cd213 ("examples/ipsec-secgw: support fragmentation and reassembly")
Cc: stable@dpdk.org

Signed-off-by: Marcin Smoczynski <490306a34ac9a546e79414e9c4162c70be9b77a9@intel.com>
Acked-by: Konstantin Ananyev <cbd5212b59ab42a210d72992d23a3aa17cfd3eaf@intel.com>
Acked-by: Akhil Goyal <74d7c4c993a22c1d4f60c46ff3d95c969a24a25c@nxp.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk