patch 8.2.5009: fold may not be closeable after appending

Problem:    Fold may not be closeable after appending.
Solution:   Set the fd_small flag to MAYBE. (Brandon Simmons, closes #10471)

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    5009,
 /**/
     5008,
 /**/