Retiring libpcp Errors

[Dave Brolley <brolley@xxxxxxxxxx>]

Hi,

I'm looking at a change which removes an unnecessary check (that the 
archives in a multi-archive context all have the same time zone. I see 
that libpcp error code/messages have been retired from time to time and 
there is a message associated with this check which is now a candidate. 
Do we offer a deprecation period before doing that?
Thanks,
Dave