Publicists repping Gil Kenan’s Poltergeist (20th Century Fox, 5.22) are declining to screen it for critics in at least one major Northeastern city.  They could always change  their minds but even this tentative decision (a) indicates the usual-usual and (b) offers a slight hint as to how good it is.  “Looks like Fox is crying ‘uncle’ by not screening this,” a friend writes.  “First casualty of the summer movie season.”  Not to mention another gravy stain on the rep of producer Sam Raimi.