[dev-python/PyQt4-pyqtconfig] new package

To be able to compile app-text/calibre, see Gentoo bug 526524.
It is not intended to be distributed as a package.
It can be removed if at least one of the following conditions is met:
- we use PyQt5 and app-text/calibre-2.*,
- someone patches Calibre,
- someone patches PyQt4.