[illumos-Developer] WEBREV: 434 kernel crash dump on comstar iscsit

[Alexander Stetsenko]

Webrev link is here:

http://cr.illumos.org/view/2y5oj5em/

This fixes crash of comstar when multiple parallel iscsi target creation 
requests happen.

Crash happened because of there was stale requests in active/waiting queues,
for instance - ONLINE request after DELETE request, DELETE request 
removed object (iscsi target)
and released its memory, so while ONLINE request processing it referred 
to freed memory or tried
to "hold"  going to die iscsi target object.

Fix is to remove stale requests from active queue while iscsitgt object 
is going to be destroyed.
(waiting queue was removed at all)

A crash is easily reproduced on hw multicore machine.