Council Regulation (EEC) No 3917/92 of 21 December 1992 extending into 1993 the application of Regulations (EEC) No 3831/90, (EEC) No 3832/90, (EEC) No 3833/90, (EEC) No 3834/90, (EEC) No 3835/90 and (EEC) No 3900/91 applying generalized tariff preferences for 1991 in respect of certain products originating in developing countries, and adding to the list of beneficiaries of such preferences