Restart select when we see a EINTR
Restart select when we see a EINTR

This fixes erratic behavior when scapy is run inside of a separate
thread or in another process.
The patch is taken from
https://bitbucket.org/secdev/scapy/issues/473/scapy-sendrecv-selects-eintr-problem-in

mytliulei/Scapy,mytliulei/Scapy