I don't know of such a library, but if you need to implement an object orientated design in C, then there are different strategies for this. Some links that might be useful:
ldeniau.web.cern.ch/ldeniau/html/oopc/oopc.html
www.planetpdf.com/codecuts/pdfs/ooc.pdf
www.bolthole.com/OO-C-programming.html
