Minor tweak to exit behavior on legacy devices.
Minor tweak to exit behavior on legacy devices.

Properly refresh the screen when exiting with the framework running.
The lua code to handle that is called while cvm is SIGSTOPP'ed, so it
doesn't help.

NickSavage/koreader,chihyang/koreader,mwoz123/koreader,Markismus/koreader,frankyifei/koreader,pazos/koreader,ashhher3/koreader,houqp/koreader,koreader/koreader,NiLuJe/koreader,koreader/koreader,robert00s/koreader,apletnev/koreader,chrox/koreader,mihailim/koreader,NiLuJe/koreader,Frenzie/koreader,poire-z/koreader,lgeek/koreader,Frenzie/koreader,poire-z/koreader,Hzj-jie/koreader