busybox

sha3: fix to conform to final SHA3 padding standard, add -a BITS option

function                                             old     new   delta
hash_file                                            331     396     +65
md5_sha1_sum_main                                    485     538     +53
packed_usage                                       30423   30464     +41
sha3_begin                                            17      31     +14
sha3_hash                                            101     110      +9
sha3_end                                              41      49      +8

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>