sites for uint64_make(), we _shouldn't_ attempt to preserve high
bits in the low-order argument; it turns out not to be what the call
sites want.
[originally from svn r8185]
to be trying harder to find a 32-bit type rather than making a
uint64 structure out of two potentially 64-bit unsigned longs. And
really I ought to be using the C99 64-bit integers anyway if they're
available. But this should do for the moment.
[originally from svn r8184]
Simon Tatham
Owen Dunn
Jacob Nevins