Unroll 64-bit checksum & copy for cache line iterations.
Unroll 64-bit checksum & copy for cache line iterations.

jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm