[interop][SwiftToCxx] fix foundation-type-not-exposed-by-default-to-cxx.swift test on Linux and Windows

Author: hyp

test/Interop/SwiftToCxx/stdlib/foundation-type-not-exposed-by-default-to-cxx.swift

@@ -3,7 +3,7 @@
 // RUN: %target-swift-frontend -typecheck %s -typecheck -module-name UseFoundation -enable-experimental-cxx-interop -emit-clang-header-path %t/UseFoundation.h
 // RUN: %FileCheck %s < %t/UseFoundation.h
 
-#if canImport(Foundation)
+// REQURES: objc_interop
 
 import Foundation
 
@@ -12,6 +12,4 @@ public enum UseFoundationEnum {
     case B
 }
 
-#endif
-
-// CHECK: class UseFoundationEnum { } SWIFT_UNAVAILABLE_MSG("Swift enum 'UseFoundationEnum' cannot be represented in C++"); 
+// CHECK: class UseFoundationEnum { } SWIFT_UNAVAILABLE_MSG("Swift enum 'UseFoundationEnum' cannot be represented in C++");