Report perfdata

[Al2Klimov]

No description provided.

[oliver]

With this change the wrong level will be reported in the first days after a new distro version has been released. Eg. if the system has Ubuntu 18.04 installed (and assuming the default warn/critical parameters), right now with this change the output will be:

OSRELEASE WARNING - newer release 'groovy' (20.10) is available; release 'bionic' will be EOL in 913 days |'release'=259200.0s;0.0;2592000.0;0.0 'eol'=-78883200.0s;-2592000.0;-604800.0

But without this change it will be:

OSRELEASE CRITICAL - newer release 'focal' (20.04 LTS) is available; release 'bionic' will be EOL in 913 days

Ie. with this change always the latest version is used for comparison, which is currently Ubuntu Groovy (20.10) which has been released three days ago (therefore the "WARNING" level). But actually Ubuntu Focal (20.04) has been released 6 months ago, and therefore a "CRITICAL" level would be better here.

Yeah, I guess it would be good to have some regression tests to catch those cases (sigh).