Upstream: fixed changing method on X-Accel-Redirect.

Previously, only r->method was changed, resulting in handling of a request
as GET within nginx itself, but not in requests to proxied servers.

See http://mailman.nginx.org/pipermail/nginx/2015-December/049518.html.

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 99ef3ae..7f377b6 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2499,6 +2499,7 @@
 
             if (r->method != NGX_HTTP_HEAD) {
                 r->method = NGX_HTTP_GET;
+                r->method_name = ngx_http_core_get_method;
             }
 
             ngx_http_internal_redirect(r, &uri, &args);