patch 9.0.0509: confusing error for "saveas" command with "nofile" buffer

Problem:    Confusing error for "saveas" command with "nofile" buffer.
Solution:   Give a clearer error message. (closes #11171)
diff --git a/src/errors.h b/src/errors.h
index 5ae55b3..7f23cc8 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -1715,8 +1715,8 @@
 EXTERN char e_no_default_font_specified_for_multi_byte_printing[]
 	INIT(= N_("E675: No default font specified for multi-byte printing."));
 #endif
-EXTERN char e_no_matching_autocommands_for_acwrite_buffer[]
-	INIT(= N_("E676: No matching autocommands for acwrite buffer"));
+EXTERN char e_no_matching_autocommands_for_buftype_str_buffer[]
+	INIT(= N_("E676: No matching autocommands for buftype=%s buffer"));
 #ifdef FEAT_SYN_HL
 EXTERN char e_error_writing_temp_file[]
 	INIT(= N_("E677: Error writing temp file"));