Paramount has officially greenlit “Mission: Impossible 3,” sticking with a July 18 start for the Tom Cruise tentpole. The go-ahead from studio chief Brad Grey followed several days of intense negotiations to rein in a budget north of $150 million and a gross payout to Cruise of 30%. While the first two pics passed $1 billion worldwide, Paramount was willing to shelve the third installment under terms that the previous Paramount administration had agreed to. The studio and Cruise, whose Cruise/Wagner Prods. has been housed at Par for more than a decade, reached a compromise Tuesday. Though the studio would not comment on the terms, the budget was trimmed by at least 10%, eliminating plans to shoot in Shanghai and several other exotic locations. Cruise also agreed to modifications on his payday.