Oops, gchar-array is just gchar*.  What we need is gchararray-array,
gchar*-array, gcharpointer-array, str-array or strv or something.  Pick your
favorite.  I picked gchar*-array for this updated patch, but feel free to
object.

This patch is nicer: I found that we can get rid of an override.  This also
returns tuples instead of lists, which is consistent with what the pygtk
overrides do.  Furthermore, I don't need to comment out the get_protocols
virtual definition since we no longer claim to be able to handle gchar**
returns.

Updated list of changes:

        * gst/arg-types.py: (StringArrayArg, StringArrayArg.write_return):
        Add support for gchar*-array return type (which occurs in the C API as
        gchar**).
        * gst/gst.defs:
        Change return type from gchar** to gchar*-array for
        GstElementFactory.get_uri_protocols, GstTypeFindFactory.get_extensions
        and GstURIHandler.get_protocols method definitions.
        * gst/gst.override: (_wrap_gst_uri_handler_get_protocols):
        Remove the now unneeded override for gst_uri_handler_get_protocols.
