Based on list discussion between myself and Geoff, it seems prudent
  to check for both the existence of the openssl/engine.h header file
  and some 'expected function' such as ENGINE_init() (better suggestions
  are welcome.)  Also clear up some confusion; so long as we have
  ENGINE_load_builtin_engines() we should attempt to preload those.

  This patch protects all ENGINE-based code within the tests for the
  engine header and function, and changes a version test into a
  function test.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100104 13f79535-47bb-0310-9956-ffa450edef68