If there is one thing the San Francisco 49ers love to do in the NFL draft , it’s drafting defensive linemen.  And after a season where they were dead last in sacks, they needed to boost the position. That’s what led them to draft two defensive linemen in this year’s draft.  The first one is Texas Tech edge rusher Romello Height . His selection was more to fill the void left by the retired Bryce Huff. They have their pass-rushing specialist on the edge set. As for the second defensive lineman drafted, they went for the interior with Oklahoma’s Gracen Halton. Taking another defensive tackle after the 49ers drafted two last year is odd, especially with Osa Odighizuwa.  However, it’s not surprising that the 49ers would draft Halton, and it’s because of how “extremely explosive” he is from the snap.…