ioapic: unexport ioapic_set_irq

There's no need to use ioapic_set_irq() outside of ioapic.c, so
make it static.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

hw/apic.h

@@ -11,7 +11,6 @@ int apic_accept_pic_intr(CPUState *env);
 void apic_deliver_pic_intr(CPUState *env, int level);
 int apic_get_interrupt(CPUState *env);
 qemu_irq *ioapic_init(void);
-void ioapic_set_irq(void *opaque, int vector, int level);
 void apic_reset_irq_delivered(void);
 int apic_get_irq_delivered(void);
 

hw/ioapic.c

@@ -94,7 +94,7 @@ static void ioapic_service(IOAPICState *s)
     }
 }
 
-void ioapic_set_irq(void *opaque, int vector, int level)
+static void ioapic_set_irq(void *opaque, int vector, int level)
 {
     IOAPICState *s = opaque;