perf data: Correctly identify directory data files

In order to rename the "header" file to "data" without conflicting,
correctly identify the non-header files as starting with "data."

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191004083121.12182-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/data.c

@@ -96,7 +96,7 @@ int perf_data__open_dir(struct perf_data *data)
 		if (stat(path, &st))
 			continue;
 
-		if (!S_ISREG(st.st_mode) || strncmp(dent->d_name, "data", 4))
+		if (!S_ISREG(st.st_mode) || strncmp(dent->d_name, "data.", 5))
 			continue;
 
 		ret = -ENOMEM;