fix installation path for *.cmake

CMakeLists.txt

@@ -170,7 +170,7 @@ file(WRITE
 
 install(FILES
         ${CMAKE_BINARY_DIR}/${CMAKE_PROJECT_NAME}Config.cmake
-        DESTINATION lib/cmake/${CMAKE_PROJECT_NAME})
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${CMAKE_PROJECT_NAME})
 
 install(EXPORT ${CMAKE_PROJECT_NAME}Targets
-        DESTINATION lib/cmake/${CMAKE_PROJECT_NAME})
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${CMAKE_PROJECT_NAME})