When the Game of Thrones series finale airs on May 19th, we’ll be witnessing an ending that the smash-hit HBO series’ showrunners have known for half a decade. Ending any TV series is no small feat, and there are a number of ways to do it. Some showrunners admit they sort of feel their way around and the series finale comes about organically, while others have had the ending meticulous mapped out for years. With regards to Game of Thrones, it’s a case of the latter. Speaking with EW, showrunners David Benioff and D.B Weiss revealed …