avfilter/showspectrum: use 0 dummies for range in const.

This is consistent with other options.

libavfilter/avf_showspectrum.c

@@ -82,9 +82,9 @@ static const AVOption showspectrum_options[] = {
         { "lin",  "linear",      0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "scale" },
     { "saturation", "color saturation multiplier", OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl = 1}, -10, 10, FLAGS },
     { "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANN}, 0, NB_WFUNC-1, FLAGS, "win_func" },
-        { "hann",     "Hann window",     0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_HANN},     INT_MIN, INT_MAX, FLAGS, "win_func" },
-        { "hamming",  "Hamming window",  0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_HAMMING},  INT_MIN, INT_MAX, FLAGS, "win_func" },
-        { "blackman", "Blackman window", 0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_BLACKMAN}, INT_MIN, INT_MAX, FLAGS, "win_func" },
+        { "hann",     "Hann window",     0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_HANN},     0, 0, FLAGS, "win_func" },
+        { "hamming",  "Hamming window",  0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_HAMMING},  0, 0, FLAGS, "win_func" },
+        { "blackman", "Blackman window", 0, AV_OPT_TYPE_CONST, {.i64 = WFUNC_BLACKMAN}, 0, 0, FLAGS, "win_func" },
     { NULL }
 };