Update P4Perl for 2005.2 API changes.
The 2005.2 API supplies forms
ready-parsed to the client when used in tagged mode. This is fine for
P4Perl, except that we were not caching the specdef if no parsing was
required and that meant that although forms could be converted to
hashes, the reverse direction was broken.
This change makes sure that we cache the specdef whenever it's
available.