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/mm/bounce.c b/mm/bounce.c
index bd1caaa..bf0cf7c 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -22,6 +22,8 @@
 
 static mempool_t *page_pool, *isa_page_pool;
 
+DEFINE_TRACE(block_bio_bounce);
+
 #ifdef CONFIG_HIGHMEM
 static __init int init_emergency_pool(void)
 {