fix LSB part of virtlogd runlevel script

fix LSB part of virtlogd runlevel script

Currently pkg build of master branch fails:

[  300s] + /usr/lib/rpm/brp-boot-scripts
[  300s] E: File `virtlogd' is missing `Required-Start', please add even if empty!
[  300s] W: File `virtlogd' is missing `Required-Stop', please add even if empty!
[  300s] E: File `virtlogd' has empty `Default-Start', please specify default runlevel(s)!
[  300s] ERROR: found one or more broken init or boot scripts, please fix them.
[  300s]        For more information about LSB headers please read the manual
[  300s]        page of of insserv by executing the command `man 8 insserv'.
[  300s]        If you don't understand this, mailto=werner@suse.de
[  300s] error: Bad exit status from /var/tmp/rpm-tmp.44965 (%install)

Add the required tags, fix the existing tags.
Use soft dependency "Should-Start" because virtlogd may work without network.

Signed-off-by: Olaf Hering <olaf@aepfle.de>