Check for <net/ethernet.h> include before enabling fd-net-device module
Bug 1712 - The IP (v4 and v6) forwarding needs a test
fix typo from changeset 9881:f6feba3e9942
Backout changeset 581c9b2f52c842a06cd3692c1a043a64b85c0c36
Revert [Coverity] Logically dead code (DEADCODE)

NS_ASSERT vanishes in optimized builds, so return code check still needed.
Bug 1727 - Ping6 should use a proper source address
Revert changeset 9854. Ipv6 forwarding should be off by default