Motion: Delete 5.3.2 Scaled-product operation

[David Hough 754R work <754r@xxxxxxxxxxx>]

Rationale:
The current specification is too limited to be worth standardizing.
Actual applications are just as likely to need over/underflow
protection for products of sums and differences.     And the array
versions would not likely be implemented upon a primitive with the prescribed
semantics (a more probable implementation primitive would return zero sf if
no over/underflow intervenes).    Since the whole point is performance,
the user feature (acting on arrays) would be implemented upon a performant
primitive.