Fix the array API unique_*() functions to not compare nans as equal
Fix the array API unique_*() functions to not compare nans as equal

The spec requires this, but it is only now possible to implement with the new
equal_nan flag in np.unique().

endolith/numpy,numpy/numpy,charris/numpy,rgommers/numpy,anntzer/numpy,endolith/numpy,numpy/numpy,mattip/numpy,mattip/numpy,mhvk/numpy,anntzer/numpy,endolith/numpy,endolith/numpy,anntzer/numpy,pdebuyl/numpy,charris/numpy,numpy/numpy,numpy/numpy,anntzer/numpy,mhvk/numpy,mhvk/numpy,pdebuyl/numpy,charris/numpy,mattip/numpy,charris/numpy,mhvk/numpy,rgommers/numpy,rgommers/numpy,mattip/numpy,rgommers/numpy,mhvk/numpy,pdebuyl/numpy,pdebuyl/numpy