flacenc: Restore defaults and range for {min,max}_prediction_order

This was broken in 243df135.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/flacenc.c

@@ -1482,8 +1482,8 @@ static const AVOption options[] = {
 { "mid_side",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_MID_SIDE    }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
 { "exact_rice_parameters", "Calculate rice parameters exactly", offsetof(FlacEncodeContext, options.exact_rice_parameters), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
 { "multi_dim_quant",       "Multi-dimensional quantization",    offsetof(FlacEncodeContext, options.multi_dim_quant),       AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
-{ "min_prediction_order", NULL, offsetof(FlacEncodeContext, options.min_prediction_order), AV_OPT_TYPE_INT, { .i64 = 0 }, MIN_LPC_ORDER, MAX_LPC_ORDER, FLAGS },
-{ "max_prediction_order", NULL, offsetof(FlacEncodeContext, options.max_prediction_order), AV_OPT_TYPE_INT, { .i64 = 0 }, MIN_LPC_ORDER, MAX_LPC_ORDER, FLAGS },
+{ "min_prediction_order", NULL, offsetof(FlacEncodeContext, options.min_prediction_order), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, MAX_LPC_ORDER, FLAGS },
+{ "max_prediction_order", NULL, offsetof(FlacEncodeContext, options.max_prediction_order), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, MAX_LPC_ORDER, FLAGS },
 
 { NULL },
 };