A southern Illinois juvenile prison closed for cost-cutting reasons may be reopened as an adult lockup for drunk driving offenders if Governor Pat Quinn has his way.  The Springfield bureau of Lee Enterprises newspapers reports Quinn announced the proposal involving the shuttered Murphysboro prison in the budget blueprint unveiled Wednesday.  Making that a reality depends on Illinois lawmakers making a 67-percent income tax increase permanent, as Quinn proposes.  Quinn’s budget office says an estimated 2,500 inmates in Illinois prisons are serving time for multiple drunk driving offenses.  Shifting them to the maximum-security lockup that closed less than two years ago in Murphysboro could ease prison crowding.  The Murphysboro youth center was built to house more than 150 inmates and once employed as many as 135 workers.