Pull up following revision(s) (requested by spz in ticket #708):
sys/conf/files: revision 1.1194
sys/dev/ic/cissvar.h: revision 1.7
sys/dev/ic/ciss.c: revision 1.38
sys/dev/pci/ciss_pci.c: revision 1.14
sys/arch/amd64/conf/ALL: revision 1.81
Add a new option CISS_NO_INTERRUPT_HACK for driving ciss(4) by callouts.
This is intended as workaround for certain Xen issues with dom0 kernels
and will likely want to have a high HZ value as well for decent
performance.

(bouyer)