system_server no longer writes to /proc/pid/oom_adj_score. This is
handled exclusively by lmkd now.

See the following commits:

Kernel 3.18:
* https://android-review.googlesource.com/139083
* https://android-review.googlesource.com/139082

Kernel 3.14:
* https://android-review.googlesource.com/139081
* https://android-review.googlesource.com/139080

Kernel 3.10:
* https://android-review.googlesource.com/139071
* https://android-review.googlesource.com/139671

Kernel 3.4:
* https://android-review.googlesource.com/139061
* https://android-review.googlesource.com/139060

Bug: 19636629
Change-Id: Ib79081365bcce4aa1190de037861a87b55c15db9