alibaba/tengine — pull request #539 by chobits (2014-11-03 09:51:16+00:00)
Title: non buffered request: rename r->request_buffering to r->request_buffering_off

* Directives proxy_request_buffering and fastcgi_request_buffering is enabled
by default, in which case r->request_buffering should be 1.

If r->request_buffering is 1 by default, we should patch all subrequest
creating functions to set this field of sub request structure.

* This commit also fixes segfault if sub requset has input body.
If uri '/lua' is requested, tengine will segfault with following configure:
```
location /memc {
set $memc_key $echo_request_uri;
set $memc_exptime 600;
memc_pass 127.0.0.1:11211;
}

location /lua {
content_by_lua '
res = ngx.location.capture("/memc",
{ method = ngx.HTTP_PUT, body = "hello" });
';
}
```