[cxx-interop] Enable a test for reference types on non-Darwin

Author: egorzhdan

test/Interop/Cxx/foreign-reference/not-any-object.swift

@@ -2,8 +2,6 @@
 // RUN: split-file %s %t
 // RUN: %target-swift-frontend -typecheck -verify -verify-ignore-unknown -I %t/Inputs  %t/test.swift  -enable-experimental-cxx-interop
 
-// REQUIRES: objc_interop
-
 //--- Inputs/module.modulemap
 module Test {
   header "test.h"