Merge r1537535 from trunk:

For better compatibility with mod_nss:

* modules/ssl/ssl_engine_config.c (ssl_config_server_new): Default
  sc->enabled to UNSET.

* modules/ssl/ssl_engine_init.c (ssl_init_Module): Only override
  sc->enabled based on the protocol iff sc->enabled is UNSET; allows
  "SSLEngine off" to override the Listen-based default.

Submitted by: jorton
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1608759 13f79535-47bb-0310-9956-ffa450edef68