Massachusetts Gov. Michael S. Dukakis has proposed deporting the illegal aliens now in his state's prisons as a measure to relieve overcrowding and save money. "I don't see any reason why the people of this state ought to be supporting folks who are here illegally in the first place," Dukakis said. State prisons and county jails hold nearly 13,000 inmates in facilities designed for 7,100, and immigrants make up 10% of the inmate population. Charles Cobb, district director for the Immigration and Naturalization Service, welcomed Dukakis' proposal and said the U.S. government could pay the inmates' outbound plane fare.