patch 8.2.4393: possible number overflow with nested folds

Problem:    Possible number overflow with nested folds.
Solution:   Avoid a negative line number.
diff --git a/src/version.c b/src/version.c
index e4bee84..4cbc297 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4393,
+/**/
     4392,
 /**/
     4391,