pgsql: Fix wrong dependency on owner created by ALTER OPCLASS OWNER.

Log Message:
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Fix wrong dependency on owner created by ALTER OPCLASS OWNER.
Per Alvaro.

Modified Files:
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pgsql/src/backend/commands:
opclasscmds.c (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/opclasscmds.c.diff?r1=1.36&r2=1.37)