DngOpcodes::DeltaRowOrColBase and friends: sanitize the lookup table values
DngOpcodes::DeltaRowOrColBase and friends: sanitize the lookup table values

Mostly for ushort16 images. The underlying problems are:
* in either case, if we are dealing with ushort16 image,
  there is a certain limited range of offsets/scales
  that won't destroy all of the image pixels.
* if scaling, the negative offset may make value negative, which
  after right shift will result in garbage

But the main reason is that i wanted to avoid f2iScale*f being
non-finite.

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