SPRINGFIELD — The Illinois Supreme Court threw out a lawsuit Thursday brought by the head of a libertarian think-tank that challenged the state’s use of bonds to pay back state debt.The decision marks the end of the legal battle initiated by Illinois Policy Institute Chairman and CEO John Tillman against the state’s use of more than $14 million in bonds to repay pension obligations and other state debt.Tillman claimed the state laws in 2003 and 2017 authorizing the bonds were unconstitutional because the bonds were not …