[epcap] epcap not starting properly when eth interface has no ipv4 address

[kvakvs]

When starting LINC on a eth-only setup (without taps and bridges), epcap does not start if interface doesn't have ipv4 address assigned (even a fake one). If you copy the command line and run it manually with -v (verbose) option, it prints something like "ethX: ipv4 address not assigned" and quits.

[kvakvs]

The error is caused by pcap_lookupnet() and is only making sense if we are using ipv4 broadcast filters (which we don't). So can safely comment out the call to pcap_lookupnet and pass 0 to pcap_compile().
This is in epcap/c_src/epcap.c lines 177-179