ldb: Add ldbdump, based on tdbdump

ldb: Add ldbdump, based on tdbdump

This uses a tdb_traverse or (more usefully) the tdb_rescue API, like tdbdump.

The difference here is that it uses ldb helper functions to further
eliminate faulty records, which avoids creating duplicates in the output.

(The duplicates come from parts of records that are left in blank space
in the db, which tdb_rescue finds, but which are not actually a full
record).

Andrew Bartlett

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Tue Oct 30 23:56:11 CET 2012 on sn-devel-104
(cherry picked from commit a71ad96bd046f1199e67b4fe8fc7783cbd8dd771)