fix peer sendfile capability

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index be30b88..987742e 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -333,7 +333,6 @@
 
     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
 
-    u->output.sendfile = c->sendfile;
     u->output.pool = r->pool;
     u->output.bufs.num = 1;
     u->output.bufs.size = clcf->client_body_buffer_size;
@@ -702,6 +701,7 @@
     c->read->handler = ngx_http_upstream_process_header;
 
     c->sendfile &= r->connection->sendfile;
+    u->output.sendfile = c->sendfile;
 
     c->pool = r->pool;
     c->read->log = c->write->log = c->log = r->connection->log;