Using Ubuntu 16.04 X86_64 Desktop -DWITH_QT=ON andI get the errors below. -DWITH_QT=OFF and OpenCV and contrib build fine.
uname -a
4.4.0-22-generic #39-Ubuntu SMP Thu May 5 16:53:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
qmake --version
QMake version 3.0 Using Qt version 5.5.1 in /usr/lib/x86_64-linux-gnu
-DWITH_QT=ON
[ 72%] Linking CXX executable ../../bin/example_cvv_cvv_demo
../../lib/libopencv_cvv.so.3.1.0: undefined reference to `QComboBox::currentTextChanged(QString const&)'
../../lib/libopencv_cvv.so.3.1.0: undefined reference to `QFrame::sizeHint() const'
../../lib/libopencv_cvv.so.3.1.0: undefined reference to `vtable for cvv::qtutil::ShowInRawView'
(More unlinked references)
collect2: error: ld returned 1 exit status
modules/cvv/CMakeFiles/example_cvv_cvv_demo.dir/build.make:103: recipe for target 'bin/example_cvv_cvv_demo' failed
make[2]: *** [bin/example_cvv_cvv_demo] Error 1
CMakeFiles/Makefile2:8976: recipe for target 'modules/cvv/CMakeFiles/example_cvv_cvv_demo.dir/all' failed
make[1]: *** [modules/cvv/CMakeFiles/example_cvv_cvv_demo.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....