[cff] Finish support for `random' operator. * src/cff/cfftypes.h (CFF_SubFontRec): Add `random' field. * src/cff/cffobjs.c: Updated. (cff_driver_init): Initialize random seed value. * src/cff/cffload.c (cff_random): New function. (cff_subfont_load): Add `face' argument. Update all callers. Initialize random number generator with a proper seed value. (cff_font_load): Add `face' argument. Update all callers. * src/cff/cffload.h: Updated. * src/cff/cf2intrp.c (CF2_FIXME): Removed. (cf2_interpT2CharString) <cf2_escRANDOM>: Implement opcode. * src/cff/cffgload.c (cff_decoder_parse_charstrings): Don't initialize random seed value. <cff_op_random>: Use new random seed framework.