syslogd, rsyslog, syslog-ng: prepare removal of syslog init script with openSUSE 12.3

This update fixes the following issue for syslogd, rsyslog and syslog-ng:
- syslogd:
- bnc#790298, bnc#750478: Reset the SYSLOG_DAEMON variable on removal only

- rsyslog, syslog-ng:
- bnc#790298, bnc#750478: Check the existence of /etc/init.d/syslog script before calling the restart_on_update and stop_on_removal macros to avoid errors on update, reset the SYSLOG_DAEMON variable on removal only. Since openSUSE 12.3, the syslog init script is not shipped any more.

Fixed bugs
bnc#750478
klogd script failur output while zypper dup
bnc#790298
removal of rsyslog failed, /etc/init.d/syslog ENOENT
Selected Binaries
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