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
Signed-off-by: Arve Hjønnevåg <arve@android.com>

Conflicts:
	drivers/staging/android/Kconfig
staging: android: lowmemorykiller: Don't count reserved free memory

The amount of reserved memory varies between devices. Subtract it
here to reduce the amount of devices specific tuning needed for the
minfree values.

Change-Id: I466ae8b18f5972f6f6d8b5a7d8c4ae69660de53a
Signed-off-by: Arve Hjønnevåg <arve@android.com>
staging: android: lowmemorykiller: Change default debug_level to 1

The select...to kill messages are not very useful when not debugging
the lowmemorykiller itself. After the change to check TIF_MEMDIE
instead of using a task notifer this message can also get very
noisy.

Change-Id: Ice171c25801d6faa454b885a23b24b002423b754
Signed-off-by: Arve Hjønnevåg <arve@android.com>
config: support oom_adj values

See https://github.com/android/kernel_common/commit/77a6bf41d0d230ce0b2bfca58ddbea6e954fe950