[PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()

IRQ_PER_CPU is not used by all architectures.  This patch introduces the
macros ARCH_HAS_IRQ_PER_CPU and CHECK_IRQ_PER_CPU() to avoid the generation
of dead code in __do_IRQ().

ARCH_HAS_IRQ_PER_CPU is defined by architectures using IRQ_PER_CPU in their
include/asm_ARCH/irq.h file.

Through grepping the tree I found the following architectures currently use
IRQ_PER_CPU:

        cris, ia64, ppc, ppc64 and parisc.

Signed-off-by: Karsten Wiese <annabellesgarden@yahoo.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-parisc/irq.h

@@ -26,6 +26,11 @@
 
 #define NR_IRQS		(CPU_IRQ_MAX + 1)
 
+/*
+ * IRQ line status macro IRQ_PER_CPU is used
+ */
+#define ARCH_HAS_IRQ_PER_CPU
+
 static __inline__ int irq_canonicalize(int irq)
 {
 	return (irq == 2) ? 9 : irq;