GOLD FRIENDS: ''Welcome to the '60s!'' said Paul Simon at L.A.'s Chandler Pavilion, where he and Art Garfunkel performed March 1 and raised $1 million for the Children's Health Fund. But the pair couldn't quite summon the Summer of Love; even after emotional duets like ''Old Friends,'' the two seemed wary of each other. ''I asked Paul,'' says Simon publicist Dan Klores, ''and he said, 'We've never looked at each other (on stage). We are not Sonny and Cher.'''