* Introduce ap_proxy_buckets_lifetime_transform as a replacement for

  proxy_buckets_lifetime_transform in mod_proxy_http. Another future consumer
  of this will be mod_proxy_wstunnel.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1726779 13f79535-47bb-0310-9956-ffa450edef68