There is no qt4 on my system. When emerging dev-util/cmake-2.8.7-r1 with USE="-qt4", the last line displayed is -- Could NOT find Qt4 (missing: QT_QMAKE_EXECUTABLE QT_MOC_EXECUTABLE QT_RCC_EXECUTABLE QT_UIC_EXECUTABLE QT_INCLUDE_DIR QT_LIBRARY_DIR QT_QTCORE_LIBRARY) Then the emerge runs into an infinite loop (100% CPU).
Found and fixed. Local problem...