[BLOCK] Only include the compat ioctl code if CONFIG_BLOCK is set

Add an extra CONFIG_BLOCK_COMPAT that we can use in the Makefile

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/Kconfig b/block/Kconfig
index 2484e0e..e108956 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -62,6 +62,10 @@
 	protocols (e.g. Task Management Functions and SMP in Serial
 	Attached SCSI).
 
+config BLOCK_COMPAT
+	bool
+	default y
+
 endif # BLOCK
 
 source block/Kconfig.iosched