[cups] how to work around API changes?

[Jacob Marble]

Context:
The following change makes API changes, so my software has to support <1.6
or >=1.6, but can't support both.
STR #3928 Add accessors for IPP APIs and make IPP structures private.

I need to support users who are building against older CUPS client APIs.
The easy way is to copy the new accessor functions into my project
(surrounded with #ifndef _CUPS_API_1_6), but that's a legal gray area.

Is there a commonly-accepted way to do this?

Thanks

Jacob Marble