samples: net: echo_client/echo_server does not work with IPv4 qemu_x86

[rlubos]

It looks like echo_server/echo_client and probably other samples that use IPv4 does not work on qemu_x86. Bisecting showed up that bab3551 broke them. It kinda makes sense, because IPv6 communication works, while IPv4 is broken.

I'm not sure what exactly is wrong in ARP as I'm not familiar with the implementation, but perhaps someone more familiar with it could take a look.

[rlubos]

CC @jukkar

[jukkar]

Thanks for a report, I will look into it.