perf data: Support single perf.data file directory

Support directory output that contains a regular perf.data file, named
"data". By default the directory is named perf.data i.e.
	perf.data
	└── data

Most of the infrastructure to support a directory is already there. This
patch makes the changes needed to support the format above.

Presently there is no 'perf record' option to output a directory.

This is preparation for adding support for putting a copy of /proc/kcore in
the directory.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191004083121.12182-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 2fb83aa..e402459 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -537,7 +537,7 @@ static int record__process_auxtrace(struct perf_tool *tool,
 	size_t padding;
 	u8 pad[8] = {0};
 
-	if (!perf_data__is_pipe(data) && !perf_data__is_dir(data)) {
+	if (!perf_data__is_pipe(data) && perf_data__is_single_file(data)) {
 		off_t file_offset;
 		int fd = perf_data__fd(data);
 		int err;