IMPORT: slz: use the generic function for the last bytes of the crc32

IMPORT: slz: use the generic function for the last bytes of the crc32

This is the only place where we conditionally use the crc32_fast table,
better call the crc32_char inline function for this. This should also
reduce by ~1kB the L1 cache footprint of the compression when dealing
with small blocks, and at least shows a consistent 0.5% perf improvement.

This is slz upstream commit 075351b6c2513b548bac37d6582e46855bc7b36f.