[rsyslog] Security Fix for 3.18.5

[Rainer Gerhards]

Hi all,

Michael Biebl made me aware that Debian Lenny uses rsyslog 3.18.5 and is
unable to move to 3.20.x due to release freeze. I have now created a
debian_lenny branch in git and backported the fixes to that branch. A
quick test succeeded. So if anyone is interested in that version, he or
she may pull it from git. If anyone finds a problem with that backport,
please let me know.

Thanks,
Rainer