af_astreamsync: remove unused variable

Signed-off-by: Jean First <jeanfirst@gmail.com>

libavfilter/af_astreamsync.c

@@ -99,7 +99,6 @@ static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     int id = outlink == ctx->outputs[1];
-    int i;
 
     outlink->sample_rate = ctx->inputs[id]->sample_rate;
     outlink->time_base   = ctx->inputs[id]->time_base;