Need workaround for lack of fromIntegral/Int->Word rules in 7.4.2

[Johan Tibell]

Hi,

Turns out that I need a larger example to trigger the bug. I can
reliable trigger it using the unordered-containers library. I won't
bore you with the details. The workaround I need is this:

    forall x. integerToWord (smallInteger x) = int2Word# x