patch 8.1.0688: text properties are not restored by undo

Problem:    Text properties are not restored by undo.
Solution:   Also save text properties for undo.
diff --git a/src/proto/memline.pro b/src/proto/memline.pro
index 3fa11c7..04254b0 100644
--- a/src/proto/memline.pro
+++ b/src/proto/memline.pro
@@ -24,7 +24,7 @@
 int ml_append(linenr_T lnum, char_u *line, colnr_T len, int newfile);
 int ml_append_buf(buf_T *buf, linenr_T lnum, char_u *line, colnr_T len, int newfile);
 int ml_replace(linenr_T lnum, char_u *line, int copy);
-int ml_replace_len(linenr_T lnum, char_u *line_arg, colnr_T len_arg, int copy);
+int ml_replace_len(linenr_T lnum, char_u *line_arg, colnr_T len_arg, int has_props, int copy);
 int ml_delete(linenr_T lnum, int message);
 void ml_setmarked(linenr_T lnum);
 linenr_T ml_firstmarked(void);