allow FIFO components to pick up ready tasks first
Add flag STARPU_SCHED_SIMPLE_FIFOS_BELOW_READY_FIRST and environment variable STARPU_SCHED_FIFO_READY_FIRST to let FIFO components pick up ready tasks first.
Add flag STARPU_SCHED_SIMPLE_FIFOS_BELOW_READY_FIRST and environment variable STARPU_SCHED_FIFO_READY_FIRST to let FIFO components pick up ready tasks first.