Sir Ian McKellen and Sir Patrick Stewart talk about their roles in Beckett’s “Waiting for Godot” and Pinter’s “No Man’s Land,” in repertory at the Cort Theatre. In “No Man’s Land,” two elderly writers, having met in a London pub, continue drinking and talking into the night. All might be well, until the return home of two younger men. In “Waiting for Godot,” two wanderers wait by a lonely tree to meet up with Mr. Godot, who they hope will change their lives for the better. Instead, another couple of eccentric travelers arrive, one man on the end of the other's rope.