crush/builder: replace printf with an empty dprintk macro

This mirrors mapper.c.

Signed-off-by: Sage Weil <sage@redhat.com>
crush: fix tree bucket functions

There are incorrect nodes' weight in tree bucket when construct tree
bucket. The tree bucket don't store item id in items array, so the tree
bucket will not work correctly. The patch fix above bugs and add a
simple test for tree bucket.

Signed-off-by: Rongze Zhu <zrzhit@gmail.com>
Merge pull request #2903 from ceph/wip-crush-tree

crush: fix tree bucket functions

Reviewed-by: Sage Weil <sage@redhat.com>