bird: Update to 2.0.7

bird: Update to 2.0.7

Update bird from 2.0.6 to 2.0.7
Changes from changelog
- BGP: Fix reconfiguration with import table
       *Change of some options requires route refresh, but when import table is
	active, channel reload is done from it instead of doing full route
	refresh. So in this case we request it internally.
- Doc: Minor documentation fixes
- Nest: Handle non-MPLS on MPLS case in recursive route update
       *When non-MPLS recursive route resolves to MPLS underlying route,
	then it should get MPLS labels from the the underlying route.
- Nest: Handle PtP links in recursive route update
       *Underlying (IGP) route may lead to PtP link, in this case it does not
	need gateway. Which is different than direct route without gateway.
       *When recursive (BGP) route uses PtP route, it should not use recursive
	next hop as immediate next hop, while for direct routes it should.
- Nest: Fix recursive route update
       *Missing cleanup can lead to dangling pointer to old next hops.

Signed-off-by: Adolf Belka <ahb.ipfire@gmail.com>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>