c++: Module lang hook overriding

c++: Module lang hook overriding

This installs stub lang hooks for modules and creates the module dump file.

	gcc/cp/
	* cp-lang.c (LANG_HOOKS_PREPROCESS_MAIN_FILE): Override.
	(LANG_HOOKS_PREPROCESS_OPTIONS): Override.
	(LANG_HOOKS_PREPROCESS_TOKEN): Override.
	* cp-objcp-common.c (cp_register_dumps): Add module dump.
	(cp_handle_option): New.
	* cp-objcp-common.h (cp_handle_option): Declare.
	(LANG_HOOKS_HANDLE_OPTION): Override.
	* cp-tree.h (module_dump_id): Declare.
	* module.cc (module_dump_id): Define.
	(module_begin_main_file, handle_module_option)
	(module_preproces_options): Stubs.