The constant may change in libavutil but the library may be compiled
against an older version, thus rejecting a value which is otherwise
supported by the new libavutil.
INT_MAX is used here to denote the max allowed value for a sample format.
The opt-test code is changed to provide a valid reference example.
{"request_sample_fmt","sample format audio decoders should prefer",OFFSET(request_sample_fmt),AV_OPT_TYPE_SAMPLE_FMT,{.i64=AV_SAMPLE_FMT_NONE},-1,AV_SAMPLE_FMT_NB-1,A|D,"request_sample_fmt"},
{"request_sample_fmt","sample format audio decoders should prefer",OFFSET(request_sample_fmt),AV_OPT_TYPE_SAMPLE_FMT,{.i64=AV_SAMPLE_FMT_NONE},-1,INT_MAX,A|D,"request_sample_fmt"},
{"sub_charenc","set input text subtitles character encoding",OFFSET(sub_charenc),AV_OPT_TYPE_STRING,{.str=NULL},CHAR_MIN,CHAR_MAX,S|D},
{"sub_charenc_mode","set input text subtitles character encoding mode",OFFSET(sub_charenc_mode),AV_OPT_TYPE_FLAGS,{.i64=FF_SUB_CHARENC_MODE_AUTOMATIC},-1,INT_MAX,S|D,"sub_charenc_mode"},