handle dst_bin_width==0 case properly (#18240)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18240
For rare cases when dst_bin_width == 0 we should just put all numbers to an arbitrary bin.
Reviewed By: csummersea
Differential Revision: D14544685
fbshipit-source-id: 02d04ff8bd1555d6cf7e7eeb1196a4ab3325a9e5
