Since openclipart package is just a bunch of images to be used as clipart, I think that media-gfx category is more appropriate than x11-misc. It's not even related to x11 at all. As an unrelated issue, but I'm explaining here just to avoid another bug report, is that I think the "pdf" USE flag is not needed for this package. There is only one PDF file inside the full tarball, and that one is inside an examples directory. It won't harm to leave that pdf file installed. I think the "pdf" USE flag should be removed.
We should discuss about making a massive move from x11-misc to correct categories, and take in account this package in that discussion. Anyway, this is not critic so we could discuss the topic and then take care of this bug.
This package moved.