block: Rename BlockDriverCompletionFunc to BlockCompletionFunc

I'll use it with block backends shortly, and the name is going to fit
badly there.  It's a block layer thing anyway, not just a block driver
thing.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/blockjob.c b/blockjob.c
index 3af0f6c..ff0908a 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -36,7 +36,7 @@
 #include "qapi-event.h"
 
 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
-                       int64_t speed, BlockDriverCompletionFunc *cb,
+                       int64_t speed, BlockCompletionFunc *cb,
                        void *opaque, Error **errp)
 {
     BlockJob *job;
@@ -155,7 +155,7 @@
 
 struct BlockCancelData {
     BlockJob *job;
-    BlockDriverCompletionFunc *cb;
+    BlockCompletionFunc *cb;
     void *opaque;
     bool cancelled;
     int ret;