Ruledit tool button menus not working on Qt6-mode
Meson based builds not affected.
The root cause for this in autotools build is lack of "-fPIC" on CXXFLAGS. As a workaround one can configure with CXXFLAGS="-fPIC". This is also the reason Qt6-client crashes on startup.
Ruledit Tool Button menus, such as setting tech requirements for other techs, do not work on Qt6-mode. They do work on Qt5-build.