* Avoid SEGFAULT as hooks->set_headers can be NULL. Furthermore do not set the

      ETag header permanently as setting it may not be desired for all responses.

Submitted by: niq, rpluem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@607838 13f79535-47bb-0310-9956-ffa450edef68