Revert "staging: android/lowmemorykiller: No need for task->signal check"

This reverts commit 3ea5f285fd560b628c18f9d343f54039c3a77051.
Revert "staging: android/lowmemorykiller: Do not kill kernel threads"

This reverts commit d7e2c0275809f9ca0c98e516bacecf1d223f633d.
Revert "staging: android/lowmemorykiller: Better mm handling"

This reverts commit fc6185a6a9fbc8ade9f0b73372bb9333187952ed.
Revert "staging: android/lowmemorykiller: Don't grab tasklist_lock"

This reverts commit 753786567bf6a7b2e5433177d76e3dbdba68dba0.
Fixup android lowmemorykiller