gst_caps_features_new() prototype is missing G_GNUC_NULL_TERMINATED

The prototype of gst_caps_features_new() does not have G_GNUC_NULL_TERMINATED. I think it should be added so the compiler will warn if you forget the trailing NULL argument noted in the docs. (Guess how I found out this was an issue? ;) )

By contrast, compare gst_structure_new(), which does have the attribute. gcc gives me a nice "warning: missing sentinel in function call" when I forget the NULL on that function.

Thanks for considering this report!