sixlowpan: (fixes #1342) Set MESH address type before CopyFrom in Deserialize

Usham Royrequested to merge
ushamroy/ns-3-dev:fix-sixlowpan-mesh-deserialize-address-type into master

SixLowPanMesh::Deserialize read the originator and final-destination address bytes with Address::CopyFrom() without first setting the address type, leaving the address UNASSIGNED. A later CopyFrom then aborted with "Type-0 addresses are reserved", surfacing in LrWpanMac::EnqueueTxQElement when running example-ping-lr-wpan-mesh-under in an asserts-enabled build.

Set the address type before CopyFrom for both m_src and m_dst.

Fix authored by Tommaso Pecorella. Verified locally: example-ping-lr-wpan-mesh-under now runs clean (5/5 pings, 0% loss).

Closes #1342 (closed).

Merge request reports