when the connection drops, c->aborted is set but generally

ap_pass_brigade returns APR_SUCCESS

content-length needs to be alert to c->aborted so that it
doesn't keep trying to pass brigades down (otherwise, you get
errors writing to the network over and over and over and ...)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97363 13f79535-47bb-0310-9956-ffa450edef68