`curl.cainfo` has no effect in php.ini

HHVM does not seem to respect the `curl.cainfo` setting in `php.ini`. Running

``` php
var_dump(ini_get('curl.cainfo'));
```

yields `false` even when that item is set in `php.ini`.

Moreover, it looks like arbitrary configuration entries are simply ignored by HHVM. Custom extensions such as `openssl.cafile` are not usable either.

When I try to set it via the `--config-value` switch, it says:

```
Possible bad config node: curl
```