Bump the blocksize up from 62 to 64 to speed up the modulo calculation.

Bump the blocksize up from 62 to 64 to speed up the modulo calculation.

Remove the old comment suggesting that it was desireable to have
blocksize+2 as a multiple of the cache line length.  That would
have made sense only if the block structure start point was always
aligned to a cache line boundary.  However, the memory allocations
are 16 byte aligned, so we don't really have control over whether
the struct spills across cache line boundaries.