In the dog days of August, even a dog gets served at Le Cirque. A woman who’d just enjoyed an “outstanding” $424 dinner with two friends there Tuesday night went to the bar to catch the end of the Yankees game, and found a large dog sitting there. The black and white Labrador-pit bull mix was perched on a stool with an unidentified dish before her and a flute of Cham pagne. “One would like to think that at a place like Le Cirque, maybe one would ‘rub elbows’ with a celeb rity, socialite, or famous politician — possibly even a writer from The Post — but no, at Le Cirque, you go to the bar to rub elbows with a dog. A giant dog at that,” the woman complained yesterday. The mutt, Darla, belongs to Marco Maccioni, whose family owns Le Cirque. Marco, who used Darla as the ring bearer at his June wedding to Sabrina Wender, then took the pampered pooch for a post-prandial mid-night stroll through Central Park.