EC-ISA: provide a 10% faster simple parity operation for (k, m=1). Add simple parity unit test for k=4,m=1
Merge pull request #2195 from apeters1971/wip-ec-isa-fast-xor

EC-ISA: provide a 10% faster simple parity operation for (k, m=1)

Reviewed-by: Loic Dachary <loic@dachary.org>