icoutils doesn't compile and/or run with latest libpng. I don't know if we can fix this at all. I already wrote a mail to the icoutils-author, but no reply.
works over here ... root@vapier root # qpkg -v -I -nc | egrep 'icoutils|libpng' media-libs/libpng-1.2.5-r1 media-libs/libpng-1.0.12-r1 media-gfx/icoutils-0.17.0 could you provide some error logs ?
Works for me now, too. Don't know what was wrong, maybe -r1 fixed it.