Modules compatibility: upstream config field.

It is to be used to track version of an upstream configuration used for
request processing.

src/http/ngx_http_upstream_round_robin.c

@@ -260,6 +260,7 @@ ngx_http_upstream_init_round_robin_peer(ngx_http_request_t *r,
 
     rrp->peers = us->peer.data;
     rrp->current = NULL;
+    rrp->config = 0;
 
     n = rrp->peers->number;
 
@@ -384,6 +385,7 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
 
     rrp->peers = peers;
     rrp->current = NULL;
+    rrp->config = 0;
 
     if (rrp->peers->number <= 8 * sizeof(uintptr_t)) {
         rrp->tried = &rrp->data;

src/http/ngx_http_upstream_round_robin.h

@@ -122,6 +122,7 @@ struct ngx_http_upstream_rr_peers_s {
 
 
 typedef struct {
+    ngx_uint_t                      config;
     ngx_http_upstream_rr_peers_t   *peers;
     ngx_http_upstream_rr_peer_t    *current;
     uintptr_t                      *tried;

src/stream/ngx_stream_upstream_round_robin.c

@@ -265,6 +265,7 @@ ngx_stream_upstream_init_round_robin_peer(ngx_stream_session_t *s,
 
     rrp->peers = us->peer.data;
     rrp->current = NULL;
+    rrp->config = 0;
 
     n = rrp->peers->number;
 
@@ -391,6 +392,7 @@ ngx_stream_upstream_create_round_robin_peer(ngx_stream_session_t *s,
 
     rrp->peers = peers;
     rrp->current = NULL;
+    rrp->config = 0;
 
     if (rrp->peers->number <= 8 * sizeof(uintptr_t)) {
         rrp->tried = &rrp->data;

src/stream/ngx_stream_upstream_round_robin.h

@@ -122,6 +122,7 @@ struct ngx_stream_upstream_rr_peers_s {
 
 
 typedef struct {
+    ngx_uint_t                       config;
     ngx_stream_upstream_rr_peers_t  *peers;
     ngx_stream_upstream_rr_peer_t   *current;
     uintptr_t                       *tried;