pgsql: Ignore RECHECK in CREATE OPERATOR CLASS, just throwing a NOTICE,

Log Message:
-----------
Ignore RECHECK in CREATE OPERATOR CLASS, just throwing a NOTICE, instead of
throwing an error as 8.4 had been doing. The error interfered with porting
old database definitions (particularly for pg_migrator) without really buying
any safety. Per bug #4817 and subsequent discussion.

Modified Files:
--------------
pgsql/src/backend/parser:
gram.y (r2.663 -> r2.664)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.663&r2=2.664)
pgsql/src/bin/pg_dump:
pg_dump.c (r1.537 -> r1.538)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c?r1=1.537&r2=1.538)