%{qmake_qt5} QXMLEDIT_INST_DIR=%{_bindir} QXMLEDIT_INST_LIB_DIR=%{_libdir} QXMLEDIT_INST_DATA_DIR=%{_datadir}/%{name} QXMLEDIT_INST_TRANSLATIONS_DIR=%{_datadir}/%{name}/translations QXMLEDIT_INST_INCLUDE_DIR=%{_includedir}/%{name} QXMLEDIT_INST_ICON_DIR=%{_datadir}/pixmaps QXMLEDIT_INST_DOC_DIR=%{_datadir}/doc/%{name} ...
Most of these "hacks" can be dropped with replacing hardcoded '/opt/' with $PREFIX. Then you can install QXmlEdit into /opt/... or /usr/local/... or ordinary /usr/...
2. Other handy installed files:install -Dm 0644 install_scripts/environment/desktop/%{bigname}.appdata.xml %{buildroot}%{_datadir}/metainfo/%{bigname}.appdata.xml
install -Dm 0644 install_scripts/environment/man/%{name}.1 %{buildroot}%{_mandir}/man1/%{name}.1