Upstream: u->length now defaults to -1 (API change).

That is, by default we assume that response end is signalled by
a connection close.  This seems to be better default, and in line
with u->pipe->length behaviour.

Memcached module was modified accordingly.

src/http/modules/ngx_http_memcached_module.c

diff --git a/src/http/modules/ngx_http_memcached_module.c b/src/http/modules/ngx_http_memcached_module.c
index c36ad0f..bfff1bf 100644
--- a/src/http/modules/ngx_http_memcached_module.c
+++ b/src/http/modules/ngx_http_memcached_module.c
@@ -441,8 +441,11 @@
     u = ctx->request->upstream;
 
     if (u->headers_in.status_n != 404) {
-        u->length += NGX_HTTP_MEMCACHED_END;
+        u->length = u->headers_in.content_length_n + NGX_HTTP_MEMCACHED_END;
         ctx->rest = NGX_HTTP_MEMCACHED_END;
+
+    } else {
+        u->length = 0;
     }
 
     return NGX_OK;

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 08c4e57..8781fdc 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -1994,7 +1994,7 @@
 
     r->headers_out.content_length_n = u->headers_in.content_length_n;
 
-    u->length = u->headers_in.content_length_n;
+    u->length = -1;
 
     return NGX_OK;
 }