block: Round up total_sectors

Since b94a2610, bdrv_getlength() is omitted when probing image. VMDK
monolithicFlat is broken by that because a file < 512 bytes can't be
read with its total_sectors truncated to 0. This patch round up the size
to BDRV_SECTOR_SIZE, when a image size is not sector aligned.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block.c

diff --git a/block.c b/block.c
index 0e96a22..6d5c804 100644
--- a/block.c
+++ b/block.c
@@ -640,7 +640,7 @@
         if (length < 0) {
             return length;
         }
-        hint = length >> BDRV_SECTOR_BITS;
+        hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
     }
 
     bs->total_sectors = hint;