[PATCH] Add cpu_relax in idle spin loop for no-hlt kernel option

If given no-hlt kernel option, ia32 idle loop turns out to be a spin loop. 
Add cpu_relax() in this spin loop because IA32 SDM recommends that a PAUSE
instruction be put in all spin loops.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/process.c

@@ -99,6 +99,8 @@ void default_idle(void)
 			safe_halt();
 		else
 			local_irq_enable();
+	} else {
+		cpu_relax();
 	}
 }