Handle the -1 case in ap_http_filter. -1 means that we have to read

all data from the socket until the socket is closed.  This has been
used to proxy www.google.com successfully, but it doesn't return anything
when used with www.yahoo.com.  Still debugging that problem.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90044 13f79535-47bb-0310-9956-ffa450edef68