batman-adv: Distributed ARP Table - add compile option

This patch makes it possible to decide whether to include DAT within the
batman-adv binary or not.
It is extremely useful when the user wants to reduce the size of the resulting
module by cutting off any not needed feature.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/Makefile b/net/batman-adv/Makefile
index 7604159..e45e3b4 100644
--- a/net/batman-adv/Makefile
+++ b/net/batman-adv/Makefile
@@ -23,7 +23,7 @@
 batman-adv-y += bitarray.o
 batman-adv-$(CONFIG_BATMAN_ADV_BLA) += bridge_loop_avoidance.o
 batman-adv-y += debugfs.o
-batman-adv-y += distributed-arp-table.o
+batman-adv-$(CONFIG_BATMAN_ADV_DAT) += distributed-arp-table.o
 batman-adv-y += gateway_client.o
 batman-adv-y += gateway_common.o
 batman-adv-y += hard-interface.o