zbar: 0.10 -> 0.22

The original upstream at http://zbar.sourceforge.net/ has not produced a
new release or a new commit on their repository in about 7 years. Most
distros (Debian, Gentoo, Arch, ...) have switched already to the more
maintained fork at https://github.com/mchehab/zbar

Update dependencies from qt4 to qt5, reducing "electrum" closure size in
the process (now only depends on one Qt version).