http: LimitRequestBody applies to proxied requests.

If f->r->proxyreq is PROXYREQ_PROXY or PROXYREQ_REVERSE in ap_http_filter(),
we are still handling the request, not the response where LimitRequestBody
does not apply.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1829642 13f79535-47bb-0310-9956-ffa450edef68