Array addition and array sum Panama benchmarks

[Roland Westrelin]

>  .vectorArrayArray             7252565.080 ops/s
>  .vectorArraySegment           6938948.826 ops/s
>  .vectorSegmentArray           4953042.042 ops/s
>  .vectorSegmentSegment         4606278.152 ops/s

I think some of the vector API tests are buggy. Shouldn't
vectorArraySegment be something like:

    public void vectorArraySegment(Data state) {
        final double[] input = state.inputArray;
        final MemorySegment output = state.outputSegment;

        for (int i = 0; i < input.length; i+=SPECIES.length()) {
            DoubleVector a = DoubleVector.fromArray(SPECIES, input, i);
            long offset = ((long)i) * (SPECIES.vectorByteSize() / SPECIES.length());
            DoubleVector b = DoubleVector.fromMemorySegment(SPECIES, output, offset, ByteOrder.nativeOrder());
            a = a.add(b);
            a.intoMemorySegment(output, offset, ByteOrder.nativeOrder());
        }
    }

because intoMemorySegment() and fromMemorySegment() take an offset and
not an index as input?

With that fixed (assuming I got this right), all vector API tests
perform about the same.

Roland.