[quartz] Set the sRGB colorspace on the IOSurface.

Enables colorspace tranformation in Core Animation. This transform
is executed on the GPU and unlike the Core Graphics one has no
affect on performance.

Fixes #5579

gdk/quartz/GdkQuartzView.c

@@ -548,6 +548,8 @@ copy_rectangle_argb32 (cairo_surface_t *dest, cairo_surface_t *source,
 
 -(void)createBackingStoreWithWidth: (CGFloat) width andHeight: (CGFloat) height
 {
+  IOSurfaceRef surface;
+
   g_return_if_fail (width && height);
 
   CVPixelBufferRelease (pixels);
@@ -555,6 +557,9 @@ copy_rectangle_argb32 (cairo_surface_t *dest, cairo_surface_t *source,
                        kCVPixelFormatType_32BGRA,
                        cfpb_props, &pixels);
 
+  surface = CVPixelBufferGetIOSurface (pixels);
+  IOSurfaceSetValue(surface, CFSTR("IOSurfaceColorSpace"),
+                    kCGColorSpaceSRGB);
 }
 
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= 10700