lowmemorykiller: Compact memory when killing processes

* Memory compaction is never invoked on Android because we avoid swap
   and don't allocate huge pages. Fix it by invoking compaction from the LMK when
   a process is killed to reduce memory fragmentation.
Revert " lowmemorykiller: Compact memory when killing processes"

This reverts commit 92cdc4b0475e708eb49725fe240e57ae3a42402d.
Linux 3.0.59-rc1