srtserversink segfaults on trivial example after recent refactoring

In 0a350c61 a refactoring was done to srt.

The change makes the code segfault on common examples like the one on https://www.collabora.com/news-and-blog/blog/2018/02/16/srt-in-gstreamer/:

srtserversink uri=srt://:8888/ <- hostname part is empty in the xample

In the code, gst_uri_get_host (srtobject->uri) will return NULL as per docs:

Get the host name from the URI or NULL if it doesn't exist.

and then g_inet_socket_address_new_from_string() will segfault on it.

CC @joykim

---

This refactoring breaking basic functionality also suggests test coverage isn't sufficient.

Are there any tests for the SRT module?