mod_proxy_http: revert spurious comment from r1853953.

No, if we read more bytes than the C-L there is really something wrong in
our (or some) HTTP input filter.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1853956 13f79535-47bb-0310-9956-ffa450edef68