patch 8.2.4839: compiler warning for unused argument

Problem:    Compiler warning for unused argument.
Solution:   Add "UNUSED".
diff --git a/src/gui_gtk_x11.c b/src/gui_gtk_x11.c
index 4460fb3..0cd6613 100644
--- a/src/gui_gtk_x11.c
+++ b/src/gui_gtk_x11.c
@@ -1314,7 +1314,7 @@
 #if defined(FEAT_XIM) || GTK_CHECK_VERSION(3,0,0)
     static gboolean
 key_release_event(GtkWidget *widget UNUSED,
-		  GdkEventKey *event,
+		  GdkEventKey *event UNUSED,
 		  gpointer data UNUSED)
 {
 # if defined(FEAT_XIM)
diff --git a/src/version.c b/src/version.c
index 1b87213..c3b6326 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4839,
+/**/
     4838,
 /**/
     4837,