Shareholder advisory firms have never liked Viacom’s corporate governance. But new reports from two major ones — Institutional Shareholder Services and Glass Lewis — are especially critical of the entertainment giant ahead of its March 14 annual meeting. Both question the board’s decision to hand the Executive Chairman title to CEO Philippe Dauman, following ailing controlling shareholder Sumner Redstone’s shift to Chairman Emeritus. They give Viacom failing grades for…