pgsql: Fix new RI operator selection code to do the right thing when

Log Message:
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Fix new RI operator selection code to do the right thing when working with
an opclass for a generic type such as ANYARRAY.  The original coding failed
to check that PK and FK columns were of the same array type.  Per discussion
with Tom Dunstan.  Also, make the code a shade more readable by not trying
to economize on variables.

Modified Files:
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    pgsql/src/backend/commands:
        tablecmds.c (r1.214 -> r1.215)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablecmds.c.diff?r1=1.214&r2=1.215)