MADRID — Sold by Wild Bunch, Emmanuelle Bercot’s “La Fille de Brest” (150 Milligrams) will open the 64th San Sebastian Festival, the highest-profile movie event in the Spanish-speaking world. The Sept. 16 opening night berth marks another step-up in status for France’s Bercot, fast emerging as one of Europe’s most prominent writer-director-actresses after her annus...