Tweak generated code message

Tweak the message indicating the location of generated code to be clear
that the code has yet to be generated.

CMakeLists.txt

@@ -23,7 +23,7 @@ if (GENERATED_SOURCE_PATH)
 else()
 	set(GSOURCE_PATH ${PROJECT_BINARY_DIR}/src/GENERATED)
 endif()
-message("Generated source code in ${GSOURCE_PATH}")
+message("Generated source code will be in ${GSOURCE_PATH}")
 
 if(NOT CPACK_GENERATOR AND NOT CMAKE_INSTALL_RPATH AND CMAKE_INSTALL_PREFIX)
 	set(CMAKE_INSTALL_RPATH ${CMAKE_INSTALL_FULL_LIBDIR})