staging: android-alarm: Support old drivers via preprocessor aliasing

Older out of tree drivers that were desgined to the Android Alarm
in-kernel API may not build due to the namespace collision fixed in
an earlier patch. Per Arve's suggestion, this patch provides
preprocessor macros that allow older drivers to build.

CC: Arve Hjønnevåg <[e-mail]>
CC: Android Kernel Team <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/android/Kconfig

···
 	help
 	  Exports the alarm interface to user-space.
 
+config ANDROID_ALARM_OLDDRV_COMPAT
+	bool "Android Alarm compatability with old drivers"
+	depends on ANDROID_INTF_ALARM
+	default n
+	help
+	  Provides preprocessor alias to aid compatability with
+	  older out-of-tree drivers that use the Android Alarm
+	  in-kernel API. This will be removed eventually.
+
 endif # if ANDROID
 
 endmenu

drivers/staging/android/android_alarm.h

···
 /* set rtc while preserving elapsed realtime */
 int android_alarm_set_rtc(const struct timespec ts);
 
+#ifdef CONFIG_ANDROID_ALARM_OLDDRV_COMPAT
+/*
+ * Some older drivers depend on the old API,
+ * so provide compatability macros for now.
+ */
+#define alarm android_alarm
+#define alarm_init(x, y, z) android_alarm_init(x, y, z)
+#define alarm_start_range(x, y, z) android_alarm_start_range(x, y, z)
+#define alarm_try_to_cancel(x) android_alarm_try_to_cancel(x)
+#define alarm_cancel(x) android_alarm_cancel(x)
+#define alarm_set_rtc(x) android_alarm_set_rtc(x)
+#endif
+
+
 #endif
 
 enum android_alarm_return_flags {