relaxing sum check for extremely small values

[grnydawn]

We read in some array ('x', for example), and 'x' has a bunch of zero and close-to-zero values (eg, 5E-310). KGEN generates a sum-check of this array, and the value of that sum-check depends on the optimization level being used in the run that generates the kernel - eg, using 'ifort' with -O0, I'll get a sum for 'x' of something like 8E-310, but with optimizations on, I get 0. This value gets saved, along with the full array.

The problem happens when we read this value and this array in on a different compiler/flag set, as the 'sum check' tests for exact equality, so changing optimization levels means our 'sum' is now different, even if just on the order of 1E-300, and it fails.