A new holiday is about to be born in America, and even before it has occurred, it has been attracting considerable publicity. No, it’s not Frank Costanza’s famous (anti-Christmas alternative) “Festivus” of “Seinfeld” fame, nor Maulana Karenga’s “Kwanza”- designed to help African Americans find a solemnity in the Christmas season beyond all the rampant, crass commercialism. Those two have already become old hat - having actually found a place on the calendar in the minds of a growing number of people. No, this time around, it will be the celebration of “Thanksgivukkah”. Actually, this holiday did happen a few times before, way back in 1888, and after this year, it will come round yet again - but only after more than 78,000 years from now. J. BROOKS SPECTOR explains.