Independently of that, do we want to switch over to storing reltuples as a string instead of converting it? I still feel uncomfortable about the amount of baggage we added to pg_dump to avoid that.
I'm obviously a 'yes' vote for string, either fixed width buffer or pg_strdup'd, for the reduced complexity. I'm not dismissing concerns about memory usage, and we could free the RelStatsInfo structure after use, but we're already not freeing the parent structures tbinfo or indxinfo, probably because they're needed right up til the end of the program, and there's no subsequent consumer for the memory that we'd be freeing up.