packet_trace: print timestamp and process name before each packet
packet_trace: print timestamp and process name before each packet

The output looks like "--- 04-01 11:46:27.392753 ivs upcall 1".

The timestamp code is taken from aim_log.c.

vezril/ivs,vezril/ivs,floodlight/ivs,vezril/ivs,floodlight/ivs,floodlight/ivs