[rsyslog] slight kernel log format inconsistency between 3.16.2 and 3.18.0

[RB]

>  So question now: what do the list members think?

I think I may be partially re-stating #4 by saying this, but I think
the most pragmatic approach would be to implement strict RFC
compliance, then add non-default options to break that in one way or
another for backwards compatibility.  Make it explicit (in the option
name and/or documentation) that by doing so they're breaking RFC 3164;
you could even request a courtesy contact to you or the list so you
could roughly track its use and thereby when you can drop it (if
ever).

Of course, that makes more code and more complexity; I'd also support
leaving people with inflexible/broken parsers out in the cold, but I'm
pretty heartless like that.