* cipher/cipher-gcm.c (ATTR_ALIGNED_64): New.
(gcmR): Move to 'gcm_table' structure.
(gcm_table): New structure for look-up table with counters before and
after.
(gcmR): New macro.
(prefetch_table): Handle input with length not multiple of 256.
(do_prefetch_tables): Modify pre- and post-table counters to unshare
look-up table pages between processes.