[PATCH] print some x86 build options during oopses

I find this handy sometimes: it makes the oops output include info as to
whether the user has selected CONFIG_PREEMPT, CONFIG_SMP or, particularly,
CONFIG_DEBUG_PAGEALLOC.  It can save one email round-trip.

arch/i386/kernel/traps.c

@@ -255,12 +255,27 @@ spinlock_t die_lock = SPIN_LOCK_UNLOCKED;
 void die(const char * str, struct pt_regs * regs, long err)
 {
 	static int die_counter;
+	int nl = 0;
 
 	console_verbose();
 	spin_lock_irq(&die_lock);
 	bust_spinlocks(1);
 	handle_BUG(regs);
 	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
+#ifdef CONFIG_PREEMPT
+	printk("PREEMPT ");
+	nl = 1;
+#endif
+#ifdef CONFIG_SMP
+	printk("SMP ");
+	nl = 1;
+#endif
+#ifdef CONFIG_DEBUG_PAGEALLOC
+	printk("DEBUG_PAGEALLOC");
+	nl = 1;
+#endif
+	if (nl)
+		printk("\n");
 	show_registers(regs);
 	bust_spinlocks(0);
 	spin_unlock_irq(&die_lock);