patch 9.0.1094: compiler warning when HAS_MESSAGE_WINDOW is not defined

Problem:    Compiler warning when HAS_MESSAGE_WINDOW is not defined.
Solution:   Add UNUSED.
diff --git a/src/version.c b/src/version.c
index 5c21f7a..95d2a6b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1094,
+/**/
     1093,
 /**/
     1092,