Difficulties building rc1 with Qt on Linux

[Philipp K. J. <ja...@ie...>]

I am encountering difficulties building the rc1 
with the Qt terminal.

During the "configure" stage, everything goes
fine, and configure tells me that the QT terminal
will be built:

  Qt terminal: yes (qt5)

But then when I run "make", the process 
eventually dies, with a complaint about the
Qt utility "uic": 

/usr/bin/uic -o ui_QtGnuplotSettings.h
qtterminal/QtGnuplotSettings.ui uic: could not find a Qt installation
of '' 

The uic tool is installed (in /usr/bin/uic),
but somehow the install seems to be broken -
when I run (at a shell prompt):

uic -v 

which should print the version number, I get
essentially the same error:

uic: could not find a Qt installation of ''

Apparently, it is more of a Qt problem, than a 
gnuplot problem. Nevertheless is there a way to 
either:
- detect the problem during "configure"
- fix the problem (better!)?

Best,

		Ph.


PS: It is absolutely AWESOME to see a
gnuplot 5.0 release candidate! Thanks
to everyone!