Add random source/destination address generation to pkt-gen.

[adrian]

Summary

It's hard to test hash distribution testing when pkt-gen only walks
IP ranges. This adds IPv4 source/destination randomization.

[hiren]

There seem to be a bunch of whitespace changes. Other than that, looks good to me.

Try to run this by luigi as he maintains this code upstream also.

tools/tools/netmap/pkt-gen.c

584

Are these all whitespace changes or something funky that phabricator is doing?

[gnn]

Do it.

[emaste]

Is this going to be committed?