lightdm-kde-greeter has config file as a package member

[Andriy Gapon]

lightdm-kde-greeter doesn't follow the pattern where a sample config is 
installed by the package and a post install action creates an actual config file 
from the sample config only if needed.

So, after a local modification:
Checking for packages with mismatched checksums:
lightdm-kde-greeter-6.0.3: /usr/local/etc/lightdm/lightdm-kde-greeter.conf

--
Andriy Gapon