cocoa: Revert dependency on VNC

In 821601ea5b02a68ada479731a4d3d07a9876632a (Make VNC support optional)
cocoa.o was moved from ui-obj-$(CONFIG_COCOA) to vnc-obj-$(CONFIG_COCOA),
adding a dependency on $(CONFIG_VNC). That must've been unintentional.

Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>

Makefile.objs

diff --git a/Makefile.objs b/Makefile.objs
index 52d8b23..509ab39 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -128,6 +128,7 @@
 
 ui-obj-y += keymaps.o
 ui-obj-$(CONFIG_SDL) += sdl.o sdl_zoom.o x_keymap.o
+ui-obj-$(CONFIG_COCOA) += cocoa.o
 ui-obj-$(CONFIG_CURSES) += curses.o
 vnc-obj-y += vnc.o d3des.o
 vnc-obj-y += vnc-enc-zlib.o vnc-enc-hextile.o
@@ -135,7 +136,6 @@
 vnc-obj-y += vnc-enc-zrle.o
 vnc-obj-$(CONFIG_VNC_TLS) += vnc-tls.o vnc-auth-vencrypt.o
 vnc-obj-$(CONFIG_VNC_SASL) += vnc-auth-sasl.o
-vnc-obj-$(CONFIG_COCOA) += cocoa.o
 ifdef CONFIG_VNC_THREAD
 vnc-obj-y += vnc-jobs-async.o
 else