Fix IO-APIC edge IRQ handling. IRQ_INPROGRESS was cleared spuriously

if a new edge happened while we were still processing the previous
one.

Then, if a _third_ edge came in, it would actually cause a reentrant
irq handler invocation, because the original INPROGRESS bit was now
lost.

This was actually seen on IDE in PIO mode.

arch/i386/kernel/irq.c

@@ -380,8 +380,9 @@ asmlinkage unsigned int do_IRQ(struct pt_regs regs)
 			break;
 		desc->status &= ~IRQ_PENDING;
 	}
-out:
 	desc->status &= ~IRQ_INPROGRESS;
+
+out:
 	/*
 	 * The ->end() handler has to deal with interrupts which got
 	 * disabled while the handler was running.
@@ -768,7 +769,7 @@ int setup_irq(unsigned int irq, struct irqaction * new)
 
 	if (!shared) {
 		desc->depth = 0;
-		desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING);
+		desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING | IRQ_INPROGRESS);
 		desc->handler->startup(irq);
 	}
 	spin_unlock_irqrestore(&desc->lock,flags);