Remove the returned-length "w" parameter from apr_bucket_heap_create()

Remove the returned-length "w" parameter from apr_bucket_heap_create()
and apr_bucket_heap_make().  It was useless, since the length is invariant
from the length passed in and from the resulting bucket's b->length.  This
takes care of a long-standing issue first brought up in February and
discussed on the dev@apr list.  (Issue #2 from the "Bucket API Cleanup
Issues" thread.)

See http://marc.theaimsgroup.com/?l=apr-dev&m=98324983126666&w=2

Reviewed by:    Ryan Bloom (concept)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91866 13f79535-47bb-0310-9956-ffa450edef68