staging: android: lowmemorykiller: Add config option to support oom_adj values

The conversion to use oom_score_adj instead of the deprecated oom_adj
values breaks existing user-space code. Add a config option to convert
oom_adj values written to oom_score_adj values if they appear to be
valid oom_adj values.

Change-Id: I68308125059b802ee2991feefb07e9703bc48549
CRs-Fixed: 389463
Signed-off-by: Arve HjÃ¸nnevÃ¥g <arve@android.com>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>