Salma Hayek Robin Marchant/Getty Images Angelina Jolie’s sons Maddox and Pax were total pros on the set of their mom’s new movie. Salma Hayek, 58, revealed that Maddox and Pax worked “hard” in their roles in the assistant director department of Without Blood, which Jolie wrote and directed, and Hayek stars in. “They work hard,”…