patch 8.0.0425: build errors when building without folding

Problem:    Build errors when building without folding.
Solution:   Add #ifdefs. (John Marriott)
diff --git a/src/version.c b/src/version.c
index b9d3d1e..b5af6be 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    425,
+/**/
     424,
 /**/
     423,