re PR preprocessor/20078 (Gcc doesn't complain about non-benign macro definitions)

re PR preprocessor/20078 (Gcc doesn't complain about non-benign macro definitions)

libcpp:
	PR preprocessor/20078
	* include/cpp-id-data.h (struct cpp_macro): Add extra_tokens
	field.
	* include/cpplib.h (SP_DIGRAPH, SP_PREV_WHITE): Define.
	(struct cpp_token): Change flags to unsigned short.
	* lex.c (_cpp_lex_direct): Initialize arg_no for CPP_PASTE tokens.
	(_cpp_equiv_tokens): Check arg_no for CPP_PASTE tokens.
	(cpp_token_val_index): Return CPP_TOKEN_FLD_ARG_NO for CPP_PASTE
	tokens.
	* macro.c (macro_real_token_count): New.
	(enter_macro_context, replace_args): Use macro_real_token_count.
	(create_iso_definition): Record whitespace surrounding and digraph
	spelling of # and ## tokens using SP_PREV_WHITE and SP_DIGRAPH.
	Set extra_tokens and save CPP_PASTE tokens with arg_no set for
	multiple consecutive ## tokens.
	(_cpp_create_definition): Initialize extra_tokens.
	(cpp_macro_definition): Use macro_real_token_count.

gcc/testsuite:
	* gcc.dg/cpp/paste16.c, gcc.dg/cpp/redef4.c: New tests.

From-SVN: r146352