openssl: replace call to OPENSSL_config

OPENSSL_config() is "strongly recommended" to use but unfortunately that
function makes an exit() call on wrongly formatted config files which
makes it hard to use in some situations. OPENSSL_config() itself calls
CONF_modules_load_file() and we use that instead and we ignore its
return code!

Reported-by: Jan Ehrhardt
Bug: http://curl.haxx.se/bug/view.cgi?id=1401