Drop the CALLS_SET_OBJECT_PROPERTY() macro

Replace it by g_set_object() as it does the same thing.

src/calls-call-selector-item.c

@@ -140,7 +140,7 @@ static void
 set_call_holder (CallsCallSelectorItem *self, CallsCallHolder *holder)
 {
   set_call_data (self, calls_call_holder_get_data (holder));
-  CALLS_SET_OBJECT_PROPERTY (self->holder, holder);
+  g_set_object (&self->holder, holder);
 }