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>

fs/bio.c

@@ -29,6 +29,8 @@
 #include <trace/block.h>
 #include <scsi/sg.h>		/* for struct sg_iovec */
 
+DEFINE_TRACE(block_split);
+
 static struct kmem_cache *bio_slab __read_mostly;
 
 static mempool_t *bio_split_pool __read_mostly;