proc-oom-priority: Set low oom_score_adj for 'ForegroundAppList'

proc-oom-priority: Set low oom_score_adj for 'ForegroundAppList'

Set low oom_score_adj of foreground app if the corresponding configuration sets.

oom_score_adj is an important indicator to choose victim
when available memory is too low.
Therefore, if specific foreground app(s) have low fixed oom_score_adj
compared to other apps, then they will be selected for victim with relatively
low probability.

Change-Id: Ic2752fb658da05d9d92a167e5a0f4d1dae411994
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>