We have to be very careful with numeric literals in the C part, in
this case 0xff (of type int = 4 bytes on Alpha) was shifted left 56
times => always zero  :-{  Using an L or UL suffix is not always
practical, because the needed size depends on conditional typedefs
somewhere else. Solution: Cast!  :-P  ghc/includes contains some more
suspicious literals, but I did not have a look at them yet.