Even more plug-in workarounds

cmake/IfcOpenShellConfig.cmake.in

@@ -1,5 +1,7 @@
 @PACKAGE_INIT@
 
+set_and_check(IFCOPENSHELL_LIBRARY_DIR "@PACKAGE_CMAKE_INSTALL_LIBDIR@")
+
 # Variable to inspect installed schema versions.
 set(IFCOPENSHELL_SCHEMA_VERSIONS @SCHEMA_VERSIONS@)
 

cmake/package_export.cmake

@@ -17,6 +17,7 @@ configure_package_config_file(
     ${CONFIG_PACKAGE_INPUT}
     ${CONFIG_PACKAGE_OUTPUT}
     INSTALL_DESTINATION ${CONFIG_PACKAGE_LOCATION}
+    PATH_VARS CMAKE_INSTALL_LIBDIR
 )
 
 install(FILES "${CONFIG_PACKAGE_OUTPUT}" "${CONFIG_VERSION_OUTPUT}" DESTINATION ${CONFIG_PACKAGE_LOCATION})