remove spurious platformsupport dependency

it's not quite clear why it was included.

however, it pulled in CoreGraphics transitively, which now has to be
done explicitly.

Change-Id: I4186f0603360645d81895d850005af01966834c5
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

src/plugins/imageformats/macjp2/macjp2.pro

@@ -2,9 +2,9 @@ TARGET  = qmacjp2
 PLUGIN_TYPE = imageformats
 PLUGIN_CLASS_NAME = QMacJp2Plugin
 
-LIBS += -framework CoreFoundation -framework ImageIO
+LIBS += -framework CoreFoundation -framework CoreGraphics -framework ImageIO
 
-QT += core-private gui-private platformsupport-private
+QT += core-private gui-private
 
 SOURCES += \
     qmacjp2handler.cpp \