ap_rgetline_core: set the number of bytes read & copied into the caller's

buffer when returning APR_ENOSPC.  This prevents seg faults in
ap_get_mime_headers_core in an error path which handles headers that are too
long.

Submitted by:	Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@99079 13f79535-47bb-0310-9956-ffa450edef68