DUBLIN -(Dow Jones)- Pharmaceutical company GlaxoSmithKline PLC (GSK) will invest EUR30 million into its Irish plant in Dungarvan, County Waterford, the company and the Irish government jointly announced Thursday. The investment will add 50 new jobs to the existing 1,450-strong staff over three years in the production of a product to aid smoking cessation. The plant will supply to all markets outside of North America, they said.