Patch for DBD::Pg pg_relcheck problem

Attached is a patch against DBD::Pg 1.20 which
fixes the driver-specific function 'table_attributes'
for use with PostgreSQL 7.3 while maintaining
backwards compatibility with older PostgreSQL
versions.

To avoid voodoo with PostgreSQL version numbers
a check is made whether pg_relcheck exists and
the appropriate query (either 7.3 or pre 7.3)
executed. Tested with 7.3 and 7.1.3.

This is hopefully a one off problem requiring this
kind of check. I haven't had a chance to look at
every function in Pg.pm, but it seems this is the
only one "broken" by 7.3.

Comments, corrections etc. welcome!

Ian Barwick
barwick@gmx.net