Ensure mlat client logging respects log rotation.
Ensure mlat client logging respects log rotation.

The parent can rotate stderr, we need to have any running mlat child
track this rotation. So have the parent direct child stderr to the
write end of a pipe, and manually forward lines from the read end
of the pipe to whatever the parent's current stderr is.

flightaware/piaware,cbgsy/piaware,flightaware/piaware,saiarcot895/piaware,meaverick/piaware,anish/piaware