MFC r268326:
Make iSCSI initiator keep Initiator Session ID (ISID) across reconnects.

Previously ISID was changed every time, that made impossible correct
persistent reservation, because reconnected session was identified as
completely new one.
MFC r268370:
Make XPT_GET_TRAN_SETTINGS to report CAM that command queueing is enabled,
but make couple changes to handle non-queued commands too, if happen.
MFC r268388:
Add XPT_ABORT support to iSCSI initiator.

While CAM does not use it normally, it is useful for targets testing.
Fix build on stable/10.