That way, we don't have to pass a "free this" indication separately.
While we're at it, don't just free the error message, *display* it in
all cases where rlc_graph_segment_list_get() fails.
(I wish more programming languages had a proper string type, including
some whose names consist solely of the third letter of the alphabet, but
I digress....)
Change-Id: I99f8b088aa19bc8fbb178bdb36d85ba5b89c06e0
Reviewed-on: https://code.wireshark.org/review/12902
Reviewed-by: Guy Harris <guy@alum.mit.edu>