#390 --txstart-time does not work correctly for UDP with --reverse

[Steve Shearer]

We use the iperf --txstart-time feature for generating custom traffic profiles. It works correctly with TCP in both directions, and with UDP it works correctly except when we use --reverse.
In the below captures we are timing the start of a -t=4 second traffic burst with different delays using --reverse. It works fine when the --txstart-time is less than the -t parameter. However when --txstart-time >= -t it looks like there is no throughput.
This could possibly be a reporting issue because further down the server log shows that throughput is in fact being delivered.