For nine years, Syrian President Bashar al-Assad has waged a brutal civil war against his enemies and allowed his friends to profit from it. Now, he’s squeezing those same allies to solidify power and ensure the economy stays afloat as the costs of rebuilding from the conflict pile up. Mr. Assad has been targeting more than a dozen pro-regime money men, in a shakedown that has touched industries from real estate, to telecommunications and energy and imparted the message that he alone dictates Syria’s future. …