alpha: nautilus - fix compile failure with gcc-4.3

init_srm_irq() deals with irq's #16 and above, but size of irq_desc
array on nautilus and some other system types is 16. So gcc-4.3
complains that "array subscript is above array bounds", even though
this function is never called on those systems.

This adds a check for NR_IRQS <= 16, which effectively optimizes
init_srm_irq() code away on problematic platforms.

Thanks to Daniel Drake <[e-mail]> for detailed analysis
of the problem.

Signed-off-by: Ivan Kokshaysky <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/alpha/kernel/irq_srm.c

···
 {
 	long i;
 
+	if (NR_IRQS <= 16)
+		return;
 	for (i = 16; i < max; ++i) {
 		if (i < 64 && ((ignore_mask >> i) & 1))
 			continue;