David Brower, the 86-year-old environmental legend, on Saturday abandoned his bid to become president of the Sierra Club, acknowledging that he didn’t have enough votes among the board of directors. He backed the nomination of Chuck McGrady, who was unanimously elected to a second one-year term. Brower, who sits on the board, had criticized the Sierra Club’s leadership in recent days, saying there has been too much emphasis on procedure rather than substance and too much activity taking place behind closed doors.