Cornell University’s faculty will be allowed to shrink over the next three years through regular turnover as the school reduces searches and appointments in order to save money. The provost, Kent Fuchs, said he would appoint a special task force to set priorities amid belt-tightening. Cornell’s move contrasts cost-cutting measures at its peers, which have largely spared their faculties. But Cornell, an Ivy League school in Ithaca, N.Y., is hurt both by the falling value of its endowment and by funding cuts from New York State and faces a budget deficit of more than $200 million.