Replace all occurences of av_mallocz_array() by av_calloc()

They do the same.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/sapenc.c

@@ -133,7 +133,7 @@ static int sap_write_header(AVFormatContext *s)
         freeaddrinfo(ai);
     }
 
-    contexts = av_mallocz_array(s->nb_streams, sizeof(AVFormatContext*));
+    contexts = av_calloc(s->nb_streams, sizeof(*contexts));
     if (!contexts) {
         ret = AVERROR(ENOMEM);
         goto fail;