Add anycrc as a soft dependency in case ISA-L isn't available. Plus we'll want it later: when we start writing down checksums, we'll need it to combine per-part checksums for MPUs. Like with crc32c, we won't provide any pure-python version as the CPU-intensiveness could present a DoS vector. Worst case, we 501 as before. Co-Authored-By: Tim Burke <tim.burke@gmail.com> Signed-off-by: Tim Burke <tim.burke@gmail.com> Change-Id: Ia05e5677a8ca89a62b142078abfb7371b1badd3f Signed-off-by: Alistair Coles <alistairncoles@gmail.com>