xen: add resend_irq_on_evtchn() definition into events.c

Define resend_irq_on_evtchn() which ia64/xen uses.
Although it isn't used by current x86/xen code, it's arch generic
so that put it into common code.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/xen/events.h b/include/xen/events.h
index d99a3e0..acd8e06 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -31,6 +31,7 @@
 void unbind_from_irqhandler(unsigned int irq, void *dev_id);
 
 void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector);
+int resend_irq_on_evtchn(unsigned int irq);
 
 static inline void notify_remote_via_evtchn(int port)
 {