Latest qrencode version available in portage is 3.3.1, while the latest upstream version is 3.4.1. Compiles and seems to work fine with a simple ebuild rename from 3.3.1 to 3.4.1.
Maintainer timeout +*qrencode-3.4.1 (31 Jan 2013) + + 31 Jan 2013; Michael Weber <xmw@gentoo.org> +qrencode-3.4.1.ebuild: + Version bump (thanks Robert Sebastian Gerus, bug 447430) +