segmenter: loose rindex()

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

libavformat/segment.c

@@ -99,8 +99,8 @@ static int seg_write_header(AVFormatContext *s)
     if (!seg->path) {
         char *t;
         seg->path = av_strdup(s->filename);
-        t = rindex(seg->path, '.');
-        if (t) t = '\0';
+        t = strrchr(seg->path, '.');
+        if (t) *t = '\0';
     }
 
     oc = avformat_alloc_context();