Missing $CALLBACK_MSG #214
Description
CALLBACK_MSG is not being set with -flto=auto, added by arch recently.
Manually disabled it: https://aur.archlinux.org/cgit/aur.git/commit/?h=way-displays&id=f1573ac0c9061609d0ff7a2ae523eb1805377656
Root cause alex-courtis/alex-c-collections#9
Consume fix and re-enable it.