tools/vm/slabinfo: introduce extended totals mode

tools/vm/slabinfo: introduce extended totals mode

Add "-X|--Xtotals" opt to output extended totals summary,
which includes:
-- totals summary
-- slabs sorted by size
-- slabs sorted by loss (waste)

Example:
=======

slabinfo --X -N 1
  Slabcache Totals
  ----------------
  Slabcaches :  91      Aliases  : 120->69  Active:  65
  Memory used: 568.3M   # Loss   :  30.4M   MRatio:     5%
  # Objects  : 920.1K   # PartObj: 161.2K   ORatio:    17%

  Per Cache    Average         Min         Max       Total
  ---------------------------------------------------------
  #Objects       14.1K           1      227.8K      920.1K
  #Slabs           533           1       11.7K       34.7K
  #PartSlab         86           0        4.3K        5.6K
  %PartSlab        24%          0%        100%         16%
  PartObjs          17           0      129.3K      161.2K
  % PartObj        17%          0%        100%         17%
  Memory          8.7M        8.1K      384.7M      568.3M
  Used            8.2M         160      366.5M      537.9M
  Loss          468.8K           0       18.2M       30.4M

  Per Object   Average         Min         Max
  ---------------------------------------------
  Memory           587           8        8.1K
  User             584           8        8.1K
  Loss               2           0          64

  Slabs sorted by size
  ----------------------
  Name                   Objects Objsize    Space Slabs/Part/Cpu  O/S O %Fr %Ef Flg
  ext4_inode_cache        211142    1736   384.7M    11732/40/10   18 3   0  95 a

  Slabs sorted by loss
  ----------------------
  Name                   Objects Objsize    Loss Slabs/Part/Cpu  O/S O %Fr %Ef Flg
  ext4_inode_cache        211142    1736    18.2M    11732/40/10   18 3   0  95 a

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>