blktrace: port to tracepoints, update

Port to the new tracepoints API: split DEFINE_TRACE() and DECLARE_TRACE()
sites. Spread them out to the usage sites, as suggested by
Mathieu Desnoyers.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d23fda1..343094c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -52,6 +52,8 @@
 	union map_info info;
 };
 
+DEFINE_TRACE(block_bio_complete);
+
 union map_info *dm_get_mapinfo(struct bio *bio)
 {
 	if (bio && bio->bi_private)