[Libre-soc-dev] validating utf-8 using vector processing

[Jacob Lifshay]

https://lemire.me/blog/2018/05/16/validating-utf-8-strings-using-as-little-as-0-7-cycles-per-byte/

They use x86 SIMD but it should be directly translatable to SimpleV. This
is another application where multiple masks with large VL could be very
useful.

UTF-8 validation is used in tons of places, e.g. parsing JSON.

Jacob