Hardcoded value for maximum password length

[mikkonie]

We have a use case where a user may authenticate with iRODS using a token in place of a password. These tokens are 64 characters long. Initially, Davrods refused to authenticate with such a password the error Password exceeds length limits (64 vs 63).

I looked into it and this is controlled by a seemingly arbitrary hardcoded limit in src/auth.c.

I fixed the issue by forking Davrods and raising the limit in the code. Everything works fine after that, so this doesn't seem to involve any iRODS or protocol specific restriction.

This may be something of a fringe use case, but nevertheless, maybe it would be reasonable to allow setting the maximum password length with an environmnent variable?