patch 8.1.1395: saving for undo may access invalid memory

Problem:    Saving for undo may access invalid memory. (Dominique Pelle)
Solution:   Set ml_line_len also when returning a constant string.

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1395,
 /**/
     1394,
 /**/