This solves two issues, one is a backref from apr-util into the
  apache namespace, and the second is the proper linkage declarations
  and their explanations.  Documented the distinction between
  AP_IMPLEMENT_HOOK_ and AP_IMPLEMENT_EXPORT_HOOK_

  This doesn't resolve any export issues within apr-util, however.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87229 13f79535-47bb-0310-9956-ffa450edef68