During the July 12 meeting of the Blanco City Council, members approved the request for rezoning of a 2-acre tract on Highway 281, formerly owned by Sam-Mar Realty, from mixed commercial/residential to industrial use.    The Planning and Zoning Commission unanimously had voted to recommend the rezoning during one of its earlier meetings. Owner Marsha Milam plans to open a craft distillery that will produce whiskey, bourbon and vodka.