Make /cache/recovery/last_log available in recovery

Create a new recovery UI option to allow the user to view
/cache/recovery/last_log for their device. This gives enhanced
debugging information which may be necessary when a failed
OTA occurs.

Bug: 18094012
Change-Id: Ic3228de96e9bfc2a0141c7aab4ce392a38140cf3
diff --git a/device.h b/device.h
index 57ec3fc..8ff4ec0 100644
--- a/device.h
+++ b/device.h
@@ -68,7 +68,7 @@
     enum BuiltinAction { NO_ACTION, REBOOT, APPLY_EXT,
                          APPLY_CACHE,   // APPLY_CACHE is deprecated; has no effect
                          APPLY_ADB_SIDELOAD, WIPE_DATA, WIPE_CACHE,
-                         REBOOT_BOOTLOADER, SHUTDOWN };
+                         REBOOT_BOOTLOADER, SHUTDOWN, READ_RECOVERY_LASTLOG };
 
     // Perform a recovery action selected from the menu.
     // 'menu_position' will be the item number of the selected menu