av_dump_format(): reduce indentation for streams

Makes it easier to identify where metadata/chapters end and streams
begin.

libavformat/dump.c

@@ -543,7 +543,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
     avcodec_string(buf, sizeof(buf), avctx, is_output);
     avcodec_free_context(&avctx);
 
-    av_log(NULL, AV_LOG_INFO, "    Stream #%d:%d", index, i);
+    av_log(NULL, AV_LOG_INFO, "  Stream #%d:%d", index, i);
 
     /* the pid is an important information, so we display it */
     /* XXX: add a generic system */