This update for mrsh fixes the following issues:

- Use systemd_ordering instead of systemd_requires: systemd is
never a strict requirement; but in case the system is scheduled
for installation together with systemd, we want systemd to be
installed prior to mrsh.

- Add pam_keyinit.so to /etc/pam.d/mrsh|mrlogind. (bsc#1144051)
To fully support the use of kernel keyrings by systemd the mrsh package must
include the pam_keyinit.so module in its mrsh and mrlogin configuration files.

- Add README.SUSE:
Describe the steps required to set up and run mrshd/mrlogind.

- Add missing services in pre/post/preun/postun scripts.

This update was imported from the SUSE:SLE-15:Update update project.