pgsql: Allow REASSIGNED OWNED to handle opclasses and opfamilies.

Log Message:
-----------
Allow REASSIGNED OWNED to handle opclasses and opfamilies.

Backpatch to 8.3, which is as far back as we have opfamilies.
The opclass portion could probably be backpatched to 8.2, when
REASSIGN OWNED was added, but for now I have not done that.

Asko Tiidumaa, with minor adjustments by me.

Modified Files:
--------------
    pgsql/src/backend/catalog:
        pg_shdepend.c (r1.41 -> r1.42)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_shdepend.c?r1=1.41&r2=1.42)
    pgsql/src/backend/commands:
        opclasscmds.c (r1.66 -> r1.67)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/opclasscmds.c?r1=1.66&r2=1.67)
    pgsql/src/include/commands:
        defrem.h (r1.101 -> r1.102)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/defrem.h?r1=1.101&r2=1.102)