dmg: use appropriate types when reading chunks

Use the right types instead of signed int:

  size_t new_size;

  This is a byte count for g_realloc() that is calculated from uint32_t
  and size_t values.

  uint32_t chunk_count;

  Use the same type as s->n_chunks, which is used together with
  chunk_count.

This patch is a cleanup and does not fix bugs.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

block/dmg.c

@@ -161,7 +161,8 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         }
 
         if (type == 0x6d697368 && count >= 244) {
-            int new_size, chunk_count;
+            size_t new_size;
+            uint32_t chunk_count;
 
             offset += 4;
             offset += 200;