In OpenSuse Leap 15.2 (and maybe others), the qwt6 header files
installed via zypper are located in /usr/include/qwt6
I also got a warning about if-endif mismatch, so I did a quick change there.
Not included in this pull request, but one could add the required packages available from the OpenSuse repository to the Readme. While maybe not minimal, I used libqt5-qtbase-devel qwt6-devel qwt6-qt5-devel libqt5-qtserialbus-devel libqt5-qtserialport-devel with zypper.
In OpenSuse Leap 15.2 (and maybe others), the qwt6 header files installed via zypper are located in /usr/include/qwt6
I also got a warning about if-endif mismatch, so I did a quick change there.
Not included in this pull request, but one could add the required packages available from the OpenSuse repository to the Readme. While maybe not minimal, I used
libqt5-qtbase-devel qwt6-devel qwt6-qt5-devel libqt5-qtserialbus-devel libqt5-qtserialport-devel
with zypper.