patch 9.0.0391: using separate delete() call instead of writefile() 'D' flag

Problem:    Using separate delete() call instead of writefile() 'D' flag.
Solution:   Use the writefile 'D' flag.
diff --git a/src/version.c b/src/version.c
index 76ce3a1..2edbe83 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    391,
+/**/
     390,
 /**/
     389,