Ozzy Osbourne definitely stopped by the Grammys on Sunday, his widow Sharon says ... telling fans she felt her late husband's presence during Post Malone 's tribute. The singer-songwriter shared a clip Monday from music's biggest night ... which captured Posty belting out Black Sabbath's hit song "War Pigs" while legendary guitarist Slash backed him up. The clip cuts between the performance and Osbourne's emotional family looking on with tears streaming down their faces. Osbourne wrote the