The cmake runs not really well : I made a mistake. Please replace SET (pluginsdatadir "/usr/lib/cairo-dock") bySET (pluginsdatadir "/usr/share/cairo-dock/plug-ins")
Strange... this line prints nothing: pkg_check_modules (GMENU_PACKAGE ${GMENU_MODULE}) I guess there is something wrong with pkg-config
Can you first remove the content of the build directory: rm -rf cairo-dock-plug-ins/build/* Then try to recompile it.
If you still have the same problem, can you try without GMenu applet? Remove the content of the build dir first and then: cmake .. -DCMAKE_INSTALL_PREFIX=/usr -Denable-gmenu=no |