Low: ipc: reduce logging about limits as long as compressed message fits

Hi Andrew, as discussed on the mailing list. I went with your proposal to downgrade the message to "info", and added a harsher warning if the compressed size exceeds 80% of the buffer - but that's only printed once too.

For what it is worth, this was triggered by bnc#838358, but you don't like private bugzilla references in the git commit logs ;-)