accesslog: resolve FIXME.

 FIXME: contextCSN could have multiple values!
        should select the one with the server's SID.

Seems this partially fixes the #121

Change-Id: I0228166091d02bd66962b76a88473e517ed1398d

servers/slapd/overlays/accesslog.c

@@ -2279,10 +2279,12 @@ static void *accesslog_db_root(void *ctx, void *arg) {
 
       a = attr_find(e_ctx->e_attrs, slap_schema.si_ad_contextCSN);
       if (a) {
-        /* FIXME: contextCSN could have multiple values!
-         * should select the one with the server's SID */
-        attr_merge_one(e, slap_schema.si_ad_entryCSN, &a->a_vals[0],
-                       &a->a_nvals[0]);
+        int i = a->a_numvals;
+        while (--i > 0)
+          if (slap_serverID == slap_csn_get_sid(a->a_vals + 1))
+            break;
+        attr_merge_one(e, slap_schema.si_ad_entryCSN, &a->a_vals[i],
+                       &a->a_nvals[i]);
         attr_merge(e, a->a_desc, a->a_vals, a->a_nvals);
       }
       be_entry_release_rw(op, e_ctx, 0);