perf thread: Adopt get_main_thread from db-export.c

Move the get_main_thread function from db-export.c to thread.c so that
it can be used elsewhere.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1464051145-19968-2-git-send-email-andi@firstfloor.org
[ Removed leftover bits from db-export.h ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/db-export.c b/tools/perf/util/db-export.c
index c9a6dc1..b0c2b5c 100644
--- a/tools/perf/util/db-export.c
+++ b/tools/perf/util/db-export.c
@@ -233,17 +233,6 @@
 	return 0;
 }
 
-static struct thread *get_main_thread(struct machine *machine, struct thread *thread)
-{
-	if (thread->pid_ == thread->tid)
-		return thread__get(thread);
-
-	if (thread->pid_ == -1)
-		return NULL;
-
-	return machine__find_thread(machine, thread->pid_, thread->pid_);
-}
-
 static int db_ids_from_al(struct db_export *dbe, struct addr_location *al,
 			  u64 *dso_db_id, u64 *sym_db_id, u64 *offset)
 {
@@ -382,7 +371,7 @@
 	if (err)
 		return err;
 
-	main_thread = get_main_thread(al->machine, thread);
+	main_thread = thread__main_thread(al->machine, thread);
 	if (main_thread)
 		comm = machine__thread_exec_comm(al->machine, main_thread);