fix set never used warnings

(This patch was modified to leave calls to stream_getl() in place, they
are necessary for the stream's internal pointer to advance to the
correct position. -- Denis)

Signed-off-by: Denis Ovsienko <infrastation@yandex.ru>

Fix gcc warnings about varables that are set but never used.

* bgpd/bgp_attr.c
  * cluster_unintern(): ret
  * transit_unintern(): ret
  * bgp_attr_default_intern(): attre
  * bgp_mp_reach_parse(): rd_high, rd_low
* bgpd/bgp_route.c
  * bgp_announce_check_rsclient(): bgp
* bgpd/bgp_zebra.c
  * zebra_read_ipv4(): ifindex
  * zebra_read_ipv6(): ifindex
* bgpd/bgpd.c
  * bgp_config_write_peer(): filter
* lib/distribute.c
  * distribute_list_all(): dist
  * distribute_list(): dist
  * distribute_list_prefix_all(): dist
  * distribute_list_prefix(): dist
* lib/if_rmap.c
  * if_rmap(): if_rmap
* lib/vty.c
  * vty_accept(): vty
* lib/zclient.c
  * zclient_read(): ret
* zebra/irdp_interface.c
  * if_group(): zi
* zebra/rt_netlink.c
  * kernel_read(): ret, sock
diff --git a/bgpd/bgp_zebra.c b/bgpd/bgp_zebra.c
index d7af349..76c519c 100644
--- a/bgpd/bgp_zebra.c
+++ b/bgpd/bgp_zebra.c
@@ -232,12 +232,10 @@
 {
   struct stream *s;
   struct zapi_ipv4 api;
-  unsigned long ifindex;
   struct in_addr nexthop;
   struct prefix_ipv4 p;
 
   s = zclient->ibuf;
-  ifindex = 0;
   nexthop.s_addr = 0;
 
   /* Type, flags, message. */
@@ -260,7 +258,7 @@
   if (CHECK_FLAG (api.message, ZAPI_MESSAGE_IFINDEX))
     {
       api.ifindex_num = stream_getc (s);
-      ifindex = stream_getl (s);
+      stream_getl (s); /* ifindex, unused */
     }
   if (CHECK_FLAG (api.message, ZAPI_MESSAGE_DISTANCE))
     api.distance = stream_getc (s);
@@ -310,12 +308,10 @@
 {
   struct stream *s;
   struct zapi_ipv6 api;
-  unsigned long ifindex;
   struct in6_addr nexthop;
   struct prefix_ipv6 p;
 
   s = zclient->ibuf;
-  ifindex = 0;
   memset (&nexthop, 0, sizeof (struct in6_addr));
 
   /* Type, flags, message. */
@@ -338,7 +334,7 @@
   if (CHECK_FLAG (api.message, ZAPI_MESSAGE_IFINDEX))
     {
       api.ifindex_num = stream_getc (s);
-      ifindex = stream_getl (s);
+      stream_getl (s); /* ifindex, unused */
     }
   if (CHECK_FLAG (api.message, ZAPI_MESSAGE_DISTANCE))
     api.distance = stream_getc (s);