Stream: style.

Explicitly initialized peer's max_conns for upstreams created with
variables similar to how it's done in http.

src/stream/ngx_stream_upstream_round_robin.c

diff --git a/src/stream/ngx_stream_upstream_round_robin.c b/src/stream/ngx_stream_upstream_round_robin.c
index 3f4bfcf..87ca301 100644
--- a/src/stream/ngx_stream_upstream_round_robin.c
+++ b/src/stream/ngx_stream_upstream_round_robin.c
@@ -347,6 +347,7 @@
         peer[0].weight = 1;
         peer[0].effective_weight = 1;
         peer[0].current_weight = 0;
+        peer[0].max_conns = 0;
         peer[0].max_fails = 1;
         peer[0].fail_timeout = 10;
         peers->peer = peer;
@@ -380,6 +381,7 @@
             peer[i].weight = 1;
             peer[i].effective_weight = 1;
             peer[i].current_weight = 0;
+            peer[i].max_conns = 0;
             peer[i].max_fails = 1;
             peer[i].fail_timeout = 10;
             *peerp = &peer[i];