"Shlockbuster!" "Borefest!" "Trainwreck!" Oliver Stone's gay sand-and-sandal epic "Alexander" got a thorough critical roasting for its Thanksgiving opening — and Times Square moviegoers yesterday seemed equally allergic to the toga turkey. Dubbed a work of artistic suicide by most critics, the $155-million flick appeared to be headed for the box-office abyss after a limp Wednesday/Thursday take of just over $8 million. "It's garbage," a bewildered Benny Fosco, 28, said after seeing the film at Loews E-Walk yesterday. "I want my money back. This is a hype. Phony as heck." The Warner Brothers release stirred controversy when it emerged that...