Genrefication in the music world can involve fierce debates over whether an act’s art could be defined as — or confined — to such terms as heavy metal, alternative, deep house or trap. That’s been going on for as long as genres have existed, yet they take on a much more serious air when it comes to the Grammy Awards . While the organization has come a long way since 1989, when the voters’ lack of familiarity with metal resulted in wizening prog-rockers Jethro Tull winning the trophy over the far more relevant Metallica, the screening committees battle long and hard over whether an artist, song or album is this or that. Those arguments likely went on all of last month during the run-up to the first Grammy voting round (which began Sept. 29), and almost certainly included the Weeknd , whose “After Hours” is one of the biggest albums of the year. While the screening committees’ membership is ostensibly secret and not available to comment, the question of where he belongs has no doubt