Add missing file (#592)

Need to update the CI to catch this kind of error.

runtime_lib/test_lib/target.h

@@ -0,0 +1,32 @@
+//===- target.h ------------------------------------------------*- C++ -*-===//
+//
+// This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// (c) Copyright 2023 Advanced Micro Devices, Inc.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef AIE_TARGET_H
+#define AIE_TARGET_H
+
+#include <list>
+#include <xaiengine.h>
+
+struct ext_mem_model_t {
+  void *virtualAddr;
+  uint64_t physicalAddr;
+  size_t size;
+  int fd;               // The file descriptor used during allocation
+  XAie_MemInst MemInst; // LibXAIE handle if necessary.  This should go away.
+};
+
+struct aie_libxaie_ctx_t {
+  XAie_Config AieConfigPtr;
+  XAie_DevInst DevInst;
+  // Some device memory allocators need this to keep track of VA->PA mappings
+  std::list<ext_mem_model_t> allocations;
+};
+
+#endif