patch 9.0.0838: compiler warnings for unused variables

Problem:    Compiler warnings for unused variables.
Solution:   Addjust #ifdef and remove unused variables. (John Marriott)
diff --git a/src/version.c b/src/version.c
index 56ccb05..6aef2c1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    838,
+/**/
     837,
 /**/
     836,