mkrootfs: Disable pam_sss

Fedora's default PAM configuration assumes SSSD is installed.  Since it
isn't, the system log is littered with errors about it:

> PAM unable to dlopen(/usr/lib64/security/pam_sss.so): /usr/lib64/security/pam_sss.so: cannot open shared object file: No such file or directory
> PAM adding faulty module: /usr/lib64/security/pam_sss.so

mkrootfs.sh

@@ -73,6 +73,8 @@ chroot "${destdir}" systemctl disable \
     systemd-homed \
     systemd-userdbd
 ln -sf /run/resolv.conf "${destdir}"/etc/resolv.conf
+grep -lR pam_sss "${destdir}"/etc/pam.d \
+    | xargs sed -i /pam_sss/d
 
 umask 0022
 mksquashfs "${destdir}" "${destdir}/boot/${dest}" \