Donald Glover and Maya Erskine are lounging in a bunker-like greenroom in the bowels of 30 Rockefeller Plaza, debating which of them would make a better assassin. & Mrs. Smith.” “Are you talking about who’s willing to kill somebody?” Glover asks, his voice rising in amused disbelief. If you’re doing it well, like ‘I drink your milkshake’” — Glover does …