Free packet out of lock.

Reduce lock contention.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Avoid to initialize column_cur_size with a temporary value

The value can be wrong in case of N(VAR)CHAR converted.
The value is assigned later in tds_get_char_data with the correct value.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>