lowmem: Add active, inactive, and swap usage in task_info

lowmem: Add active, inactive, and swap usage in task_info

Add active, inactive, and swap usage of each app in task_info structure.
This infomration will be used in get_kill_candidates_post_with_wss() function.

Active, inactive, and swap usage are counted by
  - Active usage is sum of active_anon + active_file in memcg
  - Inactive usage is sum of inactive_anon + inactive_file in memcg
  - Swap usage is a mount of swap in memcg

Change-Id: I1e96d12023eb303754a0120e18c20ee9e66a1459
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>