ProcessList: fix lmkd minfree rules

Moving CACHED_APP_MAX_ADJ to 999 without actually setting processes
to 999 results in the first LMK rule failing to kill anything ever.
Add a new constant for the oom_adj score used by the first LMK rule.

Test: lmkd no longer fails to kill adj 999 constantly
bug 123024834

Change-Id: Iaee5e7395faa897ee46eb13354f9e15a6363de9f
1 file changed