perf evlist: Steal mmap reading routine from 'perf top'

Will be used in the upcoming 'perf test' entry for the evlist mmap
routines.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index dbfcc79..2871206 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -3,6 +3,7 @@
 
 #include <linux/list.h>
 #include "../perf.h"
+#include "event.h"
 
 struct pollfd;
 
@@ -15,6 +16,7 @@
 	int		 nr_entries;
 	int		 nr_fds;
 	int		 mmap_len;
+	event_t		 event_copy;
 	struct perf_mmap *mmap;
 	struct pollfd	 *pollfd;
 };
@@ -32,4 +34,6 @@
 
 struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id);
 
+event_t *perf_evlist__read_on_cpu(struct perf_evlist *self, int cpu);
+
 #endif /* __PERF_EVLIST_H */