daemon: Fix valgrind invalid read error in db_statistics control

daemon: Fix valgrind invalid read error in db_statistics control

  ==20761== Invalid read of size 8
  ==20761==    at 0x11BE30: ctdb_ctrl_dbstatistics (ctdb_client.c:1286)
  ==20761==    by 0x12BA89: control_dbstatistics (ctdb.c:713)
  ==20761==    by 0x1312E0: main (ctdb.c:6543)
  ==20761==  Address 0x713b0d0 is 0 bytes after a block of size 560 alloc'd
  ==20761==    at 0x4C27A2E: malloc (vg_replace_malloc.c:270)
  ==20761==    by 0x5CB0954: _talloc_memdup (talloc.c:615)
  ==20761==    by 0x11395C: ctdb_control_recv (ctdb_client.c:1146)
  ==20761==    by 0x11BDD7: ctdb_ctrl_dbstatistics (ctdb_client.c:1265)
  ==20761==    by 0x12BA89: control_dbstatistics (ctdb.c:713)
  ==20761==    by 0x1312E0: main (ctdb.c:6543)

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
(Imported from commit 9aa90482f8ffbddf898eb8a900112f45d82f0930)