fixes for bulk unload issues

- fix for bug 1391641. (unload WITH DELIMITER 255 returns ERROR[15001]).
- fix for bug 1387377. (unload with [delimiter | record_separator] 0 should err).
- fix bug 1389857. (trafci unload reports incorrect number of rows unloaded).

Change-Id: I3599728426464e81178c5904563b68aa78502a0b
Merge "fixes for bulk unload issues"