[Testing] Add missing --check-prefix and mark as XFAIL

The CHECK-64 extra inhabitant tests are broken and will be fixed as a
part of #16237.

Author: davezarzycki

test/IRGen/type_layout_reference_storage_objc.swift

@@ -1,4 +1,5 @@
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -emit-ir %s | %FileCheck %s
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -emit-ir %s | %FileCheck %s --check-prefix=CHECK-%target-ptrsize
+// XFAIL: *
 
 import Foundation