avcodec/ac3enc_float: use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/ac3enc_float.c

@@ -73,7 +73,7 @@ av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
     n  = 1 << 9;
     n2 = n >> 1;
 
-    window = av_malloc(n * sizeof(*window));
+    window = av_malloc_array(n, sizeof(*window));
     if (!window) {
         av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
         return AVERROR(ENOMEM);