[BUILD] Build break with CURL 7.29.0

In file ext/src/http/client/curl/http_operation_curl.cc, the following header is included:

```
#include <curl/system.h>
```

The problem is that header does not exists in CURL 7.29.0, which is the default in Oracle Linux 7 (OL7), based on Red Hat Enterprise Linux 7 (RHEL7).

