Avoid a double copy when saving a TTEntry

Avoid a double copy when saving a TTEntry

In statement:

*tte = TTEntry(posKey32, v, t, d, m, generation, statV, kingD);

We first create a TTEntry, then we copy the temporary entry to
its final destination in *tte then we discard the TTEntry.

Instead of this assign the fields directly to the destination TTEntry.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>