perf_counter tools: Add a data file header

Add a data file header so we can transfer data between record and report.

LKML-Reference: <new-submission>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 87a1aca..55c62f4 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -65,4 +65,10 @@
 #define MAX_COUNTERS			256
 #define MAX_NR_CPUS			256
 
+struct perf_file_header {
+	__u64	version;
+	__u64	sample_type;
+	__u64	data_size;
+};
+
 #endif