Cover; cook on Low heat setting 8 to 9 hours. Remove pork from slow cooker to cutting board; let stand 5 minutes. Shred pork into chunks, using 2 forks. Skim fat from cooking liquid in slow cooker. In small bowl, mix cornstarch and water; stir into cooking liquid. Increase heat setting to High. Cook 1 to 2 minutes, stirring constantly, until gravy is thickened.