Define a new sched_op hypercall called sched_op_new, which differs from the

Define a new sched_op hypercall called sched_op_new, which differs from the
legacy hypercall in that it takes a pointer to a block of extra arguments
rather than an opaque unsigned long. The old hypercall still exists, for
backwards compatibility.

The new hypercall supports new sub-command SCHEDOP_poll, which can be used to
wait on a set of event-channel ports with an optional timeout. This is exported
in XenLinux as HYPERVISOR_poll, and used in the pcifront driver to wait on a
response from the pciback driver.

Can also be used for debuggers. :-)

Signed-off-by: Keir Fraser <keir@xensource.com>
Signed-off-by: John Levon <john.levon@sun.com>