r13616: Add new ldb functions: ldb_msg_add_steal_string() and

r13616: Add new ldb functions: ldb_msg_add_steal_string() and
ldb_msg_add_steal_value().

These try to maintain the talloc heirachy, which must be correct
otherwise talloc_steal operations of entire attribute lists fails.

This fixes the currentTime value, found by using Microsoft's dcdiag
tool (before this commit, it pointed to invalid memory, due to the
changes in -r 13606)

Andrew Bartlett
(This used to be commit 424df1bb369fddcfd358cf26dd0da9d3851d181e)