patch 8.1.1359: text property wrong after :substitute with backslash

Problem:    Text property wrong after :substitute with backslash.
Solution:   Adjust text property columns when removing backslashes.
            (closes #4397)
diff --git a/src/vim.h b/src/vim.h
index 05ad07f..153a8c6 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2571,4 +2571,8 @@
 #define SAVE_RESTORE_ICON	2
 #define SAVE_RESTORE_BOTH	(SAVE_RESTORE_TITLE | SAVE_RESTORE_ICON)
 
+// Flags for adjust_prop_columns()
+#define APC_SAVE_FOR_UNDO	1   // call u_savesub() before making changes
+#define APC_SUBSTITUTE		2   // text is replaced, not inserted
+
 #endif /* VIM__H */