AVX/AVX-512 Tuning Doesn't Payoff for LibreOffice's Calc Spreadsheets

The code is implementing the https://en.wikipedia.org/wiki/Kahan_summation_algorithm

Seems like it could be ported to orc to hide platform dependence, but it does not yet(?) emit AVX code: https://cgit.freedesktop.org/gstreamer/orc/

Yeah, AVX512 does not necessarily give faster code. Have seen interesting benchmark results running the tests of https://github.com/gnuradio/volk