The San Antonio Spurs weren’t about to give the Houston Rockets what coach Gregg Popovich considered a “double win.” Playing the Tracy McGrady-less Houston Rockets, Popovich said the Spurs entered the AT&T Center already with an advantage. If they had lost under those circumstances, “you feel doubly bad.” The Spurs beat the Rockets 90-84 Friday night, avenging an 89-81 loss earlier this month in…