Change remaining HAVE_GTK2 to FEAT_GUI_GTK.
diff --git a/src/os_unix.c b/src/os_unix.c
index cb323c8..42009e5 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -2991,7 +2991,7 @@
     }
 #  endif
 # endif
-# if defined(FEAT_X11) && (!defined(FEAT_GUI_GTK) || defined(HAVE_GTK2))
+# if defined(FEAT_X11)
     if (x11_display != NULL
 #  ifdef FEAT_XCLIPBOARD
 	    && x11_display != xterm_dpy