pgsql: Athough cube is a varlena type, nowhere was a detoasting of

Log Message:
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Athough cube is a varlena type, nowhere was a detoasting of cube's value, so
fix it.  Add macroses DatumGetNDBOX, PG_GETARG_NDBOX and PG_RETURN_NDBOX.
Backpatch for 8.2 too.

Previous versions use version 0 calling conventions. And fmgr code detoast
values for user-defined functions.

Modified Files:
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    pgsql/contrib/cube:
        cube.c (r1.31 -> r1.32)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/cube.c.diff?r1=1.31&r2=1.32)
        cubedata.h (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/cubedata.h.diff?r1=1.8&r2=1.9)