help for gnuplot build with qt5

[Tatsuro M. <tma...@ya...>]

I am now trying to build gnuplot 5.1 with Qt 5 on ubuntu 14.04.

Octave uses qt4 so that I would like to build gnuplot without uninstall qt4.

configure --with-qt=qt5 is not enough.

Include path is not set for qt5

So I set 

QT_CFLAGS='-I/usr/include/qt5/QtConcurrent -I/usr/include/qt5/QtGui -I/usr/include/qt5/QtOpenGLExtensions -I/usr/include/qt5/QtSql -I/usr/include/qt5/QtXml -I/usr/include/qt5/QtCore -I/usr/include/qt5/QtNetwork -I/usr/include/qt5/QtPlatformSupport -I/usr/include/qt5/QtTest -I/usr/include/qt5/QtDBus -I/usr/include/qt5 -I/usr/include/qt5/QtOpenGL -I/usr/include/qt5/QtPrintSupport -I/usr/include/qt5/QtWidgets' \

Compile passes but at link a lot of  undefined reference errors.
At link a lot of undefined reference errors
So I tried to add 

QT_LIBS='-L/usr/lib/x86_64-linux-gnu/qt5/plugins/accessible -L/usr/lib/x86_64-linux-gnu/qt5/plugins/generic -L/usr/lib/x86_64-linux-gnu/qt5/plugins/organizer -L/usr/lib/x86_64-linux-gnu/qt5/plugins/platformthemes  -L/usr/lib/x86_64-linux-gnu/qt5/plugins/sensorgestures -L/usr/lib/x86_64-linux-gnu/qt5/plugins/bearer -L/usr/lib/x86_64-linux-gnu/qt5/plugins/iconengines -L/usr/lib/x86_64-linux-gnu/qt5/plugins/platforminputcontexts  -L/usr/lib/x86_64-linux-gnu/qt5/plugins/printsupport -L/usr/lib/x86_64-linux-gnu/qt5/plugins/sensors -L/usr/lib/x86_64-linux-gnu/qt5/plugins/feedback -L/usr/lib/x86_64-linux-gnu/qt5/plugins/imageformats -L/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms -L/usr/lib/x86_64-linux-gnu/qt5/plugins/qmltooling -L/usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers' \

but no make sense.

Any help is appreciated.

Tatsuro