lavfi/volume: use designated initializers for the sample_fmts declaration.

libavfilter/af_volume.c

@@ -80,8 +80,7 @@ static int query_formats(AVFilterContext *ctx)
     AVFilterFormats *formats = NULL;
     AVFilterChannelLayouts *layouts;
     static const enum AVSampleFormat sample_fmts[][7] = {
-        /* PRECISION_FIXED */
-        {
+        [PRECISION_FIXED] = {
             AV_SAMPLE_FMT_U8,
             AV_SAMPLE_FMT_U8P,
             AV_SAMPLE_FMT_S16,
@@ -90,14 +89,12 @@ static int query_formats(AVFilterContext *ctx)
             AV_SAMPLE_FMT_S32P,
             AV_SAMPLE_FMT_NONE
         },
-        /* PRECISION_FLOAT */
-        {
+        [PRECISION_FLOAT] = {
             AV_SAMPLE_FMT_FLT,
             AV_SAMPLE_FMT_FLTP,
             AV_SAMPLE_FMT_NONE
         },
-        /* PRECISION_DOUBLE */
-        {
+        [PRECISION_DOUBLE] = {
             AV_SAMPLE_FMT_DBL,
             AV_SAMPLE_FMT_DBLP,
             AV_SAMPLE_FMT_NONE