patch 9.0.0039: not all systems have GDK_KEY_dead_circumflex

Problem:    Not all systems have GDK_KEY_dead_circumflex. (Hisashi T Fujinaka)
Solution:   Add an #ifdef.
diff --git a/src/version.c b/src/version.c
index 8ddbdda..b2c63c4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    39,
+/**/
     38,
 /**/
     37,