Fix typos in comments and code (occured -> occurred and related)

The code changed here is an unused data type name (evt_flush_occurred).

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/block.c b/block.c
index 8767d31..f403718 100644
--- a/block.c
+++ b/block.c
@@ -747,7 +747,7 @@
  * Run consistency checks on an image
  *
  * Returns 0 if the check could be completed (it doesn't mean that the image is
- * free of errors) or -errno when an internal error occured. The results of the
+ * free of errors) or -errno when an internal error occurred. The results of the
  * check are stored in res.
  */
 int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res)