MAINT: Use Python integers for int to array of uint32 calculation
MAINT: Use Python integers for int to array of uint32 calculation

The new weak promotion preserves the original type, this makes the
`//= 2**32` fail for certain inputs.  The alternative would be
typing that as `np.int64(2**32)`, but using Python integers seems
easier and cleaner.

The code was effectively OK before, since the inputs were guaranteed
signed (or Python integers) at that point and 2**32 would have been
considered like a NumPy `int64`.  (Which would be an alternative fix.)

mattip/numpy,charris/numpy,endolith/numpy,charris/numpy,numpy/numpy,mattip/numpy,endolith/numpy,numpy/numpy,endolith/numpy,charris/numpy,numpy/numpy,mattip/numpy,endolith/numpy,numpy/numpy,charris/numpy,mattip/numpy