[fix] alignment of footer

[mfunyu]

• Wrong size block exist

  [5] (80) |-> 0x7fc3b6aa6f50 |-> 0x7fc3b6a91640 |-> 0x7fc3b6ad8f90 |<< 88 >>
  -> 0x7fc3b6ad7dc0 |-> 0x7fc3bce1bd40 |-> 0x7fc3bce19290 |
  ----------+------------------+------------------+------------------+
  [6] (96) |-> 0x7fc3b6a91a50 |-> 0x7fc3b6acd4b0 |-> 0x7fc3bce18210 |-> 0x7fc3bce173c0 |-> 0x7fc3bce13d70 |-> 0x7fc3bce127b0 |-> 0x7fc3bce12640 |
  ----------+------------------+------------------+------------------+
  [7] (112) |-> 0x7fc3b6a85260 |-> 0x7fc3b6a78670 |-> 0x7fc3b6a93550 |-> 0x7fc3b6aa7c00 |-> 0x7fc3bce1b6d0 |-> 0x7fc3bce17720 |
  ----------+------------------+------------------+------------------+
  [8] (128) |-> 0x7fc3b6a96820 |-> 0x7fc3b6abce30 |-> 0x7fc3b6ab7900 |-> 0x7fc3b6ac3190 |-> 0x7fc3bce18640 |-> 0x7fc3bce12540 |
  ----------+------------------+------------------+------------------+
  [9] (144) |-> 0x7fc3b6a7b520 |-> 0x7fc3b6aade50 |-> 0x7fc3b6aad7b0 |-> 0x7fc3b6aabdb0 |-> 0x7fc3bce29d10 |-> 0x7fc3bce13a10 |
  ----------+------------------+------------------+------------------+
  [10] (160) |-> 0x7fc3b6a5cc90 |-> 0x7fc3b6a9c980 |-> 0x7fc3b6ab8130 |-> 0x7fc3b6ab4660 |-> 0x7fc3b6aac1f0 |-> 0x7fc3bce1fb00 |
  ----------+------------------+------------------+------------------+
  [11] (176) |-> 0x7fc3b6a5e240 |-> 0x7fc3b6a77a10 |-> 0x7fc3b6a9ff30 |-> 0x7fc3b6a98260 |-> 0x7fc3b6abeb60 |-> 0x7fc3b6ad8110 |-> 0x7fc3bce16ad0 |
  ----------+------------------+------------------+------------------+
  [12] (192) |-> 0x7fc3b6a7d370 |-> 0x7fc3bce27f30 |-> 0x7fc3bce27380 |
  ----------+------------------+------------------+------------------+
  [13] (208) |-> 0x7fc3b6a89e70 |-> 0x7fc3b6a88440 |-> 0x7fc3b6a76ff0 |-> 0x7fc3b6ab5320 |-> 0x7fc3b6ad34d0 |-> 0x7fc3bce2af10 |<< 216 >>
  -> 0x7fc3bce29890 |-> 0x7fc3bce12d30 |

• Those are the blocks right before footer blocks

  ==================++==========================+
  0x7fc3b6ad8f90   ||                          | 
  ------------------++--------------------------+
   0x7fc3b6ad8f98   ||       80 (     0x58) |-|P| size
  ------------------++--------------------------+
  0x7fc3b6ad8fa0   ||           0x7fc3b6ad7dc0 | fd
  ------------------++--------------------------+
  0x7fc3b6ad8fa8   ||           0x7fc3b6a91640 | bk
  ------------------++--------------------------+
  0x7fc3b6ad8fb0   ||                          | 
                || [        56 (     0x38)] |
  ==================++==========================+
   0x7fc3b6ad8fe8   ||                     0x58 | prev_size
  ------------------++--------------------------+
   0x7fc3b6ad8ff0   ||       -8 (      0x0) |A|-| size
  ------------------++--------------------------+
  0x7fc3b6ad8ff8   ||           0x7fc3bce12000 | fd
  ==================++==========================+

• fix footer size