clockevents: Allow build w/o run-tine usage for migration purposes

Migration aid to allow preparatory patches which introduce not yet
used parts of clock events code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index f368a6f..d2ddea9 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -8,7 +8,7 @@
 #ifndef _LINUX_CLOCKCHIPS_H
 #define _LINUX_CLOCKCHIPS_H
 
-#ifdef CONFIG_GENERIC_CLOCKEVENTS
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BUILD
 
 #include <linux/clocksource.h>
 #include <linux/cpumask.h>
@@ -126,9 +126,13 @@
 extern int clockevents_program_event(struct clock_event_device *dev,
 				     ktime_t expires, ktime_t now);
 
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
 extern void clockevents_notify(unsigned long reason, void *arg);
-
 #else
+# define clockevents_notify(reason, arg) do { } while (0)
+#endif
+
+#else /* CONFIG_GENERIC_CLOCKEVENTS_BUILD */
 
 #define clockevents_notify(reason, arg) do { } while (0)