Add support for the Qt 5 application and UI framework

Packages describing “qt5” as local USE flag

Package“qt5” Flag Description
app-i18n/fcitx-chinese-addonsEnable configure qt5
dev-libs/quazipBuild with Qt5 support
dev-python/pyudevInstall PyQt5 bindings
games-simulation/flightgearBuild Qt5 launcher application
kde-plasma/plasma-metaPull in required packages for seamless integration of KF5/Qt5-based applications
media-gfx/renderdocBuild and install the qrenderdoc GUI
media-libs/openimageioBuild iv with Qt5
media-video/guvcviewBuild with Qt5 interface instead Gtk+

All packages providing a “qt5” USE flag (93)