Stop password errors from getting reported as transfer errors

[Matt McCutchen]

On Sat, 2007-11-03 at 18:14 +0000, Wayne Davison committed:
> Stop password errors from getting reported as transfer errors.

IMO, setting log_got_error back to zero after the password handling is a
hack.  Here are two possible better approaches:

1. Decide where the real division between setup and transfer errors is
(e.g., the beginning of client_run) and reset log_got_error there.

2. Introduce a new logcode FERROR_NO23 that is the same as FERROR except
that it doesn't cause log_got_error to be set, and use this logcode for
error messages that shouldn't cause an exit code 23.

Matt