Instead of using a separate member variable, use `pid_ > 0` to determine
if the process is still running. Previously the value of `pid_` was not
reset to -1 when the process terminated, but since it is only meaningful
while the process is running, reset it to -1 in `Process::died()`.
Neither `pid_` nor `running_` are exposed, so this change has no effect
on the public interface or observable behaviour.
Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>