tests: BGP unit tests to set BGP_OPT_NO_LISTEN so they can run

BGP tests had been broken by auto-creation of listen socket. This allows
them to run at least, though at least 1 test seems to have other breakage,
aspath_test.
diff --git a/tests/bgp_mpath_test.c b/tests/bgp_mpath_test.c
index 15e450a..3d0ecb7 100644
--- a/tests/bgp_mpath_test.c
+++ b/tests/bgp_mpath_test.c
@@ -378,7 +378,8 @@
   master = thread_master_create ();
   zclient = zclient_new ();
   bgp_master_init ();
-
+  bgp_option_set (BGP_OPT_NO_LISTEN);
+  
   if (fileno (stdout) >= 0)
     tty = isatty (fileno (stdout));
   return 0;