Call CONF_modules_free() before ENGINE_cleanup() in auto-deinit

During auto de-init we were calling ENGINE_cleanup(), and then later
CONF_modules_free(). However the latter function can end up calling
engine code, which can lead to a use of the global_engine_lock after it
has already been freed. Therefore we should swap the calling order of
these two functions.

Reviewed-by: Rich Salz <rsalz@openssl.org>