perf evlist: Introduce evsel list accessors

To replace the longer list_entry constructs for things that are widely
used:

	perf_evlist__{first,last}(evlist)
	perf_evsel__next(evsel)

Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ng7azq26wg1jd801qqpcozwp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index c411b42..65f39fd 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -184,4 +184,9 @@
 
 int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
 			     struct perf_sample *sample, bool swapped);
+
+static inline struct perf_evsel *perf_evsel__next(struct perf_evsel *evsel)
+{
+	return list_entry(evsel->node.next, struct perf_evsel, node);
+}
 #endif /* __PERF_EVSEL_H */