Provide a far more useful explanation when SSLCryptoDevice fails to

  Provide a far more useful explanation when SSLCryptoDevice fails to
  find a device.  Still would be nice to implement dynamic:{options}
  but this gets us to display the usual, builtin devices.

  We now load builtin engines up front, in the pre_config phase, because
  this and any other config cmd processor must have an already valid
  library config.  So loading builtin engines becomes redundant in this
  cmd handler.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100108 13f79535-47bb-0310-9956-ffa450edef68