From the first message, it seems like the problem is higher, at the Qt build level: the uic program is linked against system Qt libraries rather than against the libraries in its build tree:
/media/vaughan/workspace/lnx/devel/Support/qt-everywhere-build-5.10.0/bin/uic: /usr/lib/x86_64-linux-gnu/libQt5Core.so.5: version `Qt_5.10’ not found (required by /media/vaughan/workspace/lnx/devel/Support/qt-everywhere-build-5.10.0/bin/uic)
So the problem is potentially with Qt or the qt-easy-build discovery process rather than Slicer per se. (but the only thing I can think of is maybe you have LD_LIBRARY_PATH set already, for a Nix or multi-arch configuration? then ld might defer to those during build as in the link from Andras).