pgsql: Make contrib/isn pass the opr_sanity sanity checks: add missing

Log Message:
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Make contrib/isn pass the opr_sanity sanity checks: add missing
commutator operators, and mark hash-opclass members as oprcanhash.
This is a pretty ugly, brute-force solution, but it seems that getting
rid of all these redundant-looking operators would require some tweaks
in the core operator-resolution code to behave nicely, and I'm not
willing to risk that just before RC1.

Modified Files:
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    pgsql/contrib/isn:
        isn.sql.in (r1.3 -> r1.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isn/isn.sql.in.diff?r1=1.3&r2=1.4)