Update to 2.5.4

- Add dkim-stats option to install dkim-stats(8) FFR
- Only install dkim-stats(8) man page if dkim-stats option has been specified

2.5.4          2008/04/17
* Skip signatures with errors in dkimf_authorsigok().
* Avoid a NULL dereference in dkimf_config_reload() when starting
without a configuration file.
* Fix an alignment problem in dkimf_checkip().  Problem reported
by Jeff A. Earickson.
* LIBDKIM: Fix bug #SF1942387: Per RFC4871, disallow "l=" values
that exceed the size of the canonicalized message body.

2.5.3          2008/04/14
* Add "AllowSHA1Only" configuration option which permits operation
of verifiers that only know about SHA1.  Without this, a
filter compiled with only SHA1 support will refuse to start
in verifier mode.
* Add "LogWhy" configuration parameter and "-W" command line flag
to request detailed logging about why a message was not
signed by the filter.  Intended for debugging; not intended
for normal operation.
* Another tweak to parameters passed to db->open().  Based on patches
from Jukka Salmi and S. Moonesamy.
* Fixes in ares_parse() to match the current syntax.  In particular,
deal with the fact that some of our tokens can legally appear
in e-mail addresses.  Problem noted by S. Moonesamy of
Eland Systems.
* LIBDKIM: Evaluate key granularity against the "i=" value rather than
the value of the From: header per RFC4871.  Problem noted by
Jason Long.
* LIBDKIM: Remove the chartable stuff from dkim-tables.c as it is
not used anywhere.
* LIBDKIM: Fix bug #SF1940302: Perform stronger validation of the value
of the "h=" tag.

(adrianp)