Add Joe's RCU. Original patch from Joe Korty.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Added optimized CRC32 algorithm.
Revert "Add Joe's RCU. Original patch from Joe Korty."

This reverts commit 9e2e918c861963dae62acf6a68a1c09303000f8f.