Improves performance slightly.

Fixes "hw csum failure" log spam in batman-adv.

Updates batman-adv and alfred to 2017.1. This also allows us to drop our
last batman-adv patch.

Also remove our own no_rebroadcast patch, as batman-adv v2016.5 now has a
more sophisticated rebroadcast suppression that should work automatically
in the most relevant cases.

Fixes a build issue when switching targets.

This lifts batman-adv and alfred to version 2016.4.

Introduce new fixes:

 * Avoid nullptr dereference in bla after vlan_insert_tag
 * Avoid nullptr dereference in dat after vlan_insert_tag
 * Avoid tt_req_node list put for unhashed entry
 * Fix orig_node_vlan leak on orig_node_release
 * Fix non-atomic bla_claim::backbone_gw access
 * Fix reference leak in batadv_find_router
 * Free last_bonding_candidate on release of orig_node

Also replace the gluon version of the speedyjoin patch with the one already
included in openwrt-routing.

Signed-off-by: Sven Eckelmann <sven.eckelmann@open-mesh.com>

Speedy join only works when the received packet is either broadcast or an
4addr unicast packet. Thus packets converted from broadcast to unicast via
the gateway handling code have to be converted to 4addr packets to allow
the receiving gateway server to add the sender address as temporary entry
to the translation table.

Not doing it will make the batman-adv gateway server drop the DHCP response
in many situations because it doesn't yet have the TT entry for the
destination of the DHCP response.

Signed-off-by: Sven Eckelmann <sven@narfation.org>

batman-adv & alfred 2016.2.

Should be redundant after 0bd0df6f

This also updates batman-adv & alfred to 2015.1

This should workaround batman-adv's inability to deal with different MTUs
which need fragmentation.

Fixes #435

This gets us an up-to-date alfred (and batman-adv 2014.x, as soon as we start to
support it).