President Clinton Thursday praised Philip Morris Cos. for offering an alternative to the Food & Drug Administration's proposals to severely limit tobacco advertising. Speaking at a forum on corporate responsibility, the President said he still hopes for a legislative alternative to a long fight over agency regulation. Philip Morris, which on Wednesday offered to abide by certain ad restrictions as an alternative to FDA regulation, tomorrow breaks new advertising called "a common ground solution." In newspaper ads, the company will detail its proposals as responding to the President's request to join in the debate on how to curb underage smoking. Young & Rubicam, New York, handles PM's corporate advertising.