Proxy: allocate $proxy_internal_body_length from request pool.

src/http/modules/ngx_http_proxy_module.c

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index eadc8c4..892ee27 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -2076,7 +2076,7 @@
     v->no_cacheable = 0;
     v->not_found = 0;
 
-    v->data = ngx_pnalloc(r->connection->pool, NGX_OFF_T_LEN);
+    v->data = ngx_pnalloc(r->pool, NGX_OFF_T_LEN);
 
     if (v->data == NULL) {
         return NGX_ERROR;