perf session: Move the global threads list to perf_session

So that we can process two perf.data files.

We still need to add a O_MMAP mode for perf_session so that we
can do all the mmap stuff in it.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1260741029-4430-5-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/data_map.c b/tools/perf/util/data_map.c
index ba2eb2c..44dea21 100644
--- a/tools/perf/util/data_map.c
+++ b/tools/perf/util/data_map.c
@@ -125,9 +125,9 @@
 	return err;
 }
 
-static struct thread *perf_session__register_idle_thread(struct perf_session *self __used)
+static struct thread *perf_session__register_idle_thread(struct perf_session *self)
 {
-	struct thread *thread = threads__findnew(0);
+	struct thread *thread = perf_session__findnew(self, 0);
 
 	if (!thread || thread__set_comm(thread, "swapper")) {
 		pr_err("problem inserting idle task.\n");