gnu: ibus-minimal: Disable GTK 2 support.

* gnu/packages/ibus.scm (ibus-minimal) [configure-flags]: Add
'--disable-gtk2'.
[inputs]: Remove gtk+-2.

gnu/packages/ibus.scm

@@ -90,7 +90,8 @@
     (outputs '("out" "doc"))
     (arguments
      (list
-      #:configure-flags #~(list "--enable-gtk-doc"
+      #:configure-flags #~(list "--disable-gtk2"
+                                "--enable-gtk-doc"
                                 "--enable-memconf"
                                 (string-append
                                  "--with-unicode-emoji-dir="
@@ -194,7 +195,6 @@
            dbus
            dconf
            glib
-           gtk+-2
            gtk+
            iso-codes
            json-glib