bgpd: fix struct attr_extra leak in bgp_default_originate()

  The call to bgp_attr_default_set() above creates the attr_extra struct,
but the attr.extra = NULL initialization was leaking it.

Signed-off-by: Jorge Boncompte [DTI2] <jorge@dti2.net>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 68eae6a..a421fd7 100644
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -2488,12 +2488,8 @@
 #ifdef HAVE_IPV6
   else if (afi == AFI_IP6)
     {
-      struct attr_extra *ae;
-      attr.extra = NULL;
-      
-      ae = bgp_attr_extra_get (&attr);
-      attr.extra = ae;
-      
+      struct attr_extra *ae = attr.extra;
+
       str2prefix ("::/0", &p);
 
       /* IPv6 global nexthop must be included. */