Based on list discussion between myself and Geoff, it seems prudent

  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