lowmemmorykiller: port from kernel 3.4 (https://github.com/android/kernel_common)

Change-Id: Ifb83f799aa089a5448815a268bf415042ab643ea
Revert "default scheduler: VR"

This reverts commit 208cb564a2eba4593dd6561637d3871b4ef458ba.
Revert "reorganize config, cleanup doubled sync drivers, enable sync"

This reverts commit 78b965bc5d0e50bd1296ef40a6892cc42c3ab517.
sync: remove doubled driver from staging section
defconfig: correct configuration now ..
Dyn Fsync: Enable by default - disables Async Fsync