Upstream: removed rudiments of upstream connection caching.

This functionality is now provided by ngx_http_upstream_keepalive_module.
diff --git a/src/http/ngx_http_upstream_round_robin.c b/src/http/ngx_http_upstream_round_robin.c
index d1331f4..d786ed1 100644
--- a/src/http/ngx_http_upstream_round_robin.c
+++ b/src/http/ngx_http_upstream_round_robin.c
@@ -373,7 +373,6 @@
 
     ngx_int_t                      rc;
     ngx_uint_t                     i, n;
-    ngx_connection_t              *c;
     ngx_http_upstream_rr_peer_t   *peer;
     ngx_http_upstream_rr_peers_t  *peers;
 
@@ -382,26 +381,6 @@
 
     /* ngx_lock_mutex(rrp->peers->mutex); */
 
-    if (rrp->peers->last_cached) {
-
-        /* cached connection */
-
-        c = rrp->peers->cached[rrp->peers->last_cached];
-        rrp->peers->last_cached--;
-
-        /* ngx_unlock_mutex(ppr->peers->mutex); */
-
-#if (NGX_THREADS)
-        c->read->lock = c->read->own_lock;
-        c->write->lock = c->write->own_lock;
-#endif
-
-        pc->connection = c;
-        pc->cached = 1;
-
-        return NGX_OK;
-    }
-
     pc->cached = 0;
     pc->connection = NULL;
 
diff --git a/src/http/ngx_http_upstream_round_robin.h b/src/http/ngx_http_upstream_round_robin.h
index 3f8cbf8..ea90ab9 100644
--- a/src/http/ngx_http_upstream_round_robin.h
+++ b/src/http/ngx_http_upstream_round_robin.h
@@ -42,10 +42,8 @@
 
 struct ngx_http_upstream_rr_peers_s {
     ngx_uint_t                      number;
-    ngx_uint_t                      last_cached;
 
  /* ngx_mutex_t                    *mutex; */
-    ngx_connection_t              **cached;
 
     ngx_uint_t                      total_weight;