smoothstreamingenc: Ignore the return value from mkdir

We don't need to return an error if the directory already existed.
We make sure that the directory actually is properly writeable later
within ism_write_header by writing a manifest anyway.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/smoothstreamingenc.c

@@ -285,12 +285,7 @@ static int ism_write_header(AVFormatContext *s)
     int ret = 0, i;
     AVOutputFormat *oformat;
 
-    ret = mkdir(s->filename, 0777);
-    if (ret) {
-        av_log(s, AV_LOG_ERROR, "mkdir(%s): %s\n", s->filename, strerror(errno));
-        return AVERROR(errno);
-    }
-    ret = 0;
+    mkdir(s->filename, 0777);
 
     oformat = av_guess_format("ismv", NULL, NULL);
     if (!oformat) {