bgpd: more SAFI fixes

(with resolved conflict in bgpd/bgp_packet.c)

Two macros resolving to the same integer constant broke a case block and
a more thorough merge of BGP_SAFI_VPNV4 and BGP_SAFI_VPNV6 was
performed.

* bgpd.h: MPLS-labeled VPN SAFI is AFI-independent, switch to single
* macro
* bgp_capability_test.c: update test data
* bgp_mp_attr_test.c: idem
* bgp_route.c: (bgp_maximum_prefix_overflow, bgp_table_stats_vty) update
  macro and check conditions (where appropriate)
* bgp_packet.c: (bgp_route_refresh_send, bgp_capability_send,
  bgp_update_receive, bgp_route_refresh_receive): idem
* bgp_open.c: (bgp_capability_vty_out, bgp_afi_safi_valid_indices,
  bgp_open_capability_orf, bgp_open_capability): idem
* bgp_attr.c: (bgp_mp_reach_parse, bgp_packet_attribute,
  bgp_packet_withdraw): idem
diff --git a/tests/bgp_capability_test.c b/tests/bgp_capability_test.c
index 0dbf4fb..9b43159 100644
--- a/tests/bgp_capability_test.c
+++ b/tests/bgp_capability_test.c
@@ -96,10 +96,10 @@
   },
   /* 6 */
   { "MP3",
-    "MP IP6/VPNv4",
+    "MP IP6/MPLS-labeled VPN",
     { CAPABILITY_CODE_MP, 0x4, 0x0, 0x2, 0x0, 0x80 },
-    6, SHOULD_PARSE, 0, /* parses, but invalid afi,safi */
-    1, AFI_IP6, BGP_SAFI_VPNV4, INVALID_AFI,
+    6, SHOULD_PARSE, 0,
+    1, AFI_IP6, SAFI_MPLS_LABELED_VPN, VALID_AFI,
   },
   /* 7 */
   { "MP5",
@@ -110,21 +110,14 @@
   },
   /* 8 */
   { "MP6",
-    "MP IP4/VPNv4",
+    "MP IP4/MPLS-laveled VPN",
     { CAPABILITY_CODE_MP, 0x4, 0x0, 0x1, 0x0, 0x80 },
     6, SHOULD_PARSE, 0,
-    1, AFI_IP, BGP_SAFI_VPNV4, VALID_AFI,
+    1, AFI_IP, SAFI_MPLS_LABELED_VPN, VALID_AFI,
   },  
-  /* 9 */
-  { "MP7",
-    "MP IP4/VPNv6",
-    { CAPABILITY_CODE_MP, 0x4, 0x0, 0x1, 0x0, 0x81 },
-    6, SHOULD_PARSE, 0, /* parses, but invalid afi,safi tuple */
-    1, AFI_IP, BGP_SAFI_VPNV6, INVALID_AFI,
-  },
   /* 10 */
   { "MP8",
-    "MP unknown AFI",
+    "MP unknown AFI/SAFI",
     { CAPABILITY_CODE_MP, 0x4, 0x0, 0xa, 0x0, 0x81 },
     6, SHOULD_PARSE, 0,
     1, 0xa, 0x81, INVALID_AFI, /* parses, but unknown */