patch 8.1.0691: text properties are not adjusted for :substitute

Problem:    Text properties are not adjusted for :substitute.
Solution:   Adjust text properties as well as possible.
diff --git a/src/proto/textprop.pro b/src/proto/textprop.pro
index 5a648c4..0eac557 100644
--- a/src/proto/textprop.pro
+++ b/src/proto/textprop.pro
@@ -14,4 +14,5 @@
 void clear_global_prop_types(void);
 void clear_buf_prop_types(buf_T *buf);
 void adjust_prop_columns(linenr_T lnum, colnr_T col, int bytes_added);
+void adjust_props_for_split(linenr_T lnum, int kept, int deleted);
 /* vim: set ft=c : */