Scheduler: fix wrong handling of incoming queue.
Scheduler: fix wrong handling of incoming queue.

Under high load with many invalid (not finished) connections, the
scheduler incoming queue may generate invalid references.

This patch solves the problem validating the sched node status.

Signed-off-by: Eduardo Silva <81f705dc2ce1a61a2621e0e4b442a9474e1d0c70@monkey.io>

sbagmeijer/monkey,dougsko/monkey,WilliamRen/monkey-1,sujayraaj/monkey,WilliamRen/monkey-1,sujayraaj/monkeyTest,WilliamRen/monkey-1,dreamsxin/monkey,monkey/monkey,WilliamRen/monkey-1,dougsko/monkey,monkey/monkey,dreamsxin/monkey,WilliamRen/monkey-1,dreamsxin/monkey,sujayraaj/monkey_rtems,dougsko/monkey,monkey/monkey,sbagmeijer/monkey,dreamsxin/monkey,sbagmeijer/monkey,monkey/monkey,sujayraaj/monkeyTest,sujayraaj/monkey_rtems,sujayraaj/monkey,sujayraaj/monkeyTest,sbagmeijer/monkey,dougsko/monkey,sujayraaj/monkey_rtems,sbagmeijer/monkey,sujayraaj/monkeyTest,monkey/monkey,dreamsxin/monkey,monkey/monkey,dougsko/monkey,sujayraaj/monkey_rtems,sujayraaj/monkey,sujayraaj/monkey,sujayraaj/monkey,sujayraaj/monkey_rtems