lowmemorykiller: sync with stable branch

Signed-off-by: Keff <funnykeff91@gmail.com>
+ testing: screen on/off values for lowmemorykiller.c ...

port from voku@dorimanx
block: row: hardcode values research by the community, you guys know …
…who you are.

port from franciscofranco => https://github.com/franciscofranco/Tuna_JB_pre1/commit/184bde7a8deee649130821817853c993ec06e7b0
lulzactive: tune for more aggressive

Signed-off-by: Keff <funnykeff91@gmail.com>