patch 8.0.0388: filtering lines changes folds

Problem:    filtering lines through "cat", without changing the line count,
            changes manual folds.
Solution:   Change how marks and folds are adjusted. (Matthew Malcomson, from
            neovim #6194.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    388,
 /**/
     387,
 /**/