* cpplex.c (parse_name): Might have to glue a CPP_OTHER token
	before the name.
	(lex_line): Glue @ onto the beginning of identifiers and
	string constants, in Objective-C mode.
	(output_token, spell_token): Handle CPP_OSTRING.
	(can_paste, maybe_paste_with_next): Handle pasting @ onto the
	beginning of a NAME or a STRING, in objc mode.

	* cpplib.c (get_define_node): Do not permit identifiers that
	begin with @ to be #defined.
	* cppmacro.c (CAN_PASTE_AFTER): Add CPP_OTHER.
	* cpplib.h (TTYPE_TABLE): Add CPP_OSTRING.

	* c-lang.c, objc/objc-act.c (build_objc_string): Delete.
	* c-tree.h (build_objc_string): Delete prototype.
	* objc/objc-tree.def: Delete OBJC_STRING_CST.
	* c-lex.c (yylex): Use build_string for all three kinds of strings.

	* gcc.dg/cpp/20000625-2.c: Don't expect a warning on line 4.

From-SVN: r35470