#1032 app_data field of DBT structure is not always copied when call bdb_bt_compare

[Emilien Lemaire]

When using BDB to handle indexed files, the collating sequence function is saved either in the app_data field of a DBT structure (as of writing for version 4.1 and upward), or in a bdb_app_data static variable.
In the former case, depending on the size of the record, the app_data field would not be copied to the DBT structure passed to bdb_bt_compare which would cause an error to be triggered:
bdb_bt_compare was set but no collating sequence was stored in DBT.

[Emilien Lemaire]

The bug seems to be present on all BDB versions, I tested with version 6 and 18 and got the same result

[Simon Sobisch]

fixed with [r5398]