Description of problem: 

rkhunter does not recognise the PermitRootLogin parameter when it is set in 
/etc/ssh/sshd_config.d/local.conf


Version-Release number of selected component (if applicable):  1.4.6


How reproducible:

Happens with every day's rkhunter scan


Steps to Reproduce:
1. sudo rkhunter --cronjob --nocolors --report-warnings-only


Actual results:   

Warning: The SSH configuration option 'PermitRootLogin' has not been set.
         The default value may be 'yes', to allow root access.


Expected results: No warnings reported


Additional info:


Here is the output of a grep run showing that PermitRootLogin is set in 
/etc/ssh/sshd_config.d/local.conf and not in /etc/ssh/sshd_config

$ sudo grep PermitRootLogin /etc/ssh/sshd_config \
> /etc/ssh/sshd_config.d/local.conf
/etc/ssh/sshd_config:#PermitRootLogin prohibit-password
/etc/ssh/sshd_config:# the setting of "PermitRootLogin without-password".
/etc/ssh/sshd_config.d/local.conf:PermitRootLogin yes