Photo: J. Countess/Getty Images So much of Lena Dunham’s new book is about the agony of being in the public eye that it’s hard to understand why she would shuffle into the spotlight again. But shuffle she has, writing a second memoir, Famesick , that’s out today. When she tells her mother, the artist Laurie Simmons, that she wants to write about her life again, Simmons moans, “Oh, Lena … It just sounds so sad.” Dunham is as candid as ever — the words “shocking constipation” appear alongside