* cp-tree.h (fndecl_as_string, type_as_string,
	type_as_string_real, args_as_string, decl_as_string,
	expr_as_string, code_as_string, language_as_string,
	parm_as_string, op_as_string, assop_as_string, cv_as_string,
	lang_decl_name, cp_file_of, lang_printable_name): Constify a char*.

	* errfn.c (cp_printer): Likewise.

	* error.c (cp_printer, fndecl_as_string, type_as_string_real,
	type_as_string, expr_as_string, decl_as_string, lang_decl_name,
	cp_file_of, code_as_string, language_as_string, parm_as_string,
	op_as_string, assop_as_string, args_as_string, cv_as_string):
	Likewise.

	* tree.c (lang_printable_name): Likewise.

From-SVN: r28968