Optimise 61.nfstickle to write the tickles more efficiently.

Optimise 61.nfstickle to write the tickles more efficiently.

Currently the file for each IP address is reopened to append the
details of each source socket.

This optimisation puts all the logic into awk, including the matching
of output lines from netstat.  The source sockets for each for each
destination IP are written into an array entry and then each array
entry is written to the corresponding file in a single operation.

Signed-off-by: Martin Schwenke <martin@meltin.net>