Add compiler:c++11-lang to USES to fix build on GCC-based systems:
/usr/local/include/qt5/QtCore/qglobal.h:45:25: error: type_traits: No such file or directory /usr/local/include/qt5/QtCore/qcompilerdetection.h:564:6: error: #error Qt requires a C++11 compiler and yours does not seem to be that.
Approved by: portmgr (tier-2 blanket)