Fix the 32-bit encodeReal and decodeReal in Data.Encoding.GenBinary
Casting to/from a lazy tuple doesn't work, because the layout is different. A Real on 32-bit systems is REAL,r1,r2 where r1,r2 is the double; a lazy tuple is TUPLE,p1,p2 where p1 and p2 are pointers to other nodes (in this case integers with layout INT,i).