Peter O'Toole, the 70-year-old ''Lawrence of Arabia'' star, had been nominated for seven Oscars but had never won. When his honorary Oscar was announced a few weeks ago, he played coy over whether he'd show up to collect what may have looked like a consolation prize. But show he did, and delivered a brief, gracious, and witty speech that brought the crowd to its feet. As he put it, ''Always a bridesmaid, never a bride, my foot!''