ldb-samba: critical bugfix on original recursive search implementation

ldb-samba: critical bugfix on original recursive search implementation

In the original patch (listed previously), when the search recurses it
will inevitably reallocate the visited list to a new array in memory.
When this happens the original patch didn't update it's reference to the
array.

This patch adds an extra level of indirection on the visited list in
order to fix this bug.

Signed-off-by: Adrian Cochrane <adrianc@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>