This fixes a segmentation fault if the pcap is too small.

[sn0cr]

Hi @emmericp,

during my testing with small pcaps (containing only the TCP handshake) I found that the replay-pcap example crashes Moongen with a SegFault. With this change this should not happen (at least this is the simplest change to mitigate it)

[emmericp]

Hmm, the root cause of this is something else; __ipairs shouldn't return nil buffers.

[emmericp]

Can you send me an example pcap to reproduce this? Or put it in your home directory on one of the persistent servers

[holzingk]

Possibly related #240

[shuwens]

I can confirm that this patch/PR is required for replaying a pcap trace in rate limiting mode to work. Not sure about the size part tho. The trace I am using is 100M.

[holzingk]

I sent @emmericp an example pcap via email. Hope it gets fixed soon.