KVM: SVM: Coalesce userspace/kernel irqchip interrupt injection logic

Start to use interrupt/exception queues like VMX does.
This also fix the bug that if exit was caused by a guest
internal exception access to IDT the exception was not
reinjected.

Use EVENTINJ to inject interrupts.  Use VINT only for detecting when IRQ
windows is open again.  EVENTINJ ensures
the interrupt is injected immediately and not delayed.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>