Fix the PPAPI build on AArch64.

ppapi/tests/test_struct_sizes.c

 /* Copyright (c) 2010 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * This test ensures (at compile time) that some types have the expected size in
  * C.  The purpose is to ensure that the ABI of PPAPI is known, consistent, and
  * stable.  Only structs that have architecture-dependent size are checked by
  * this test.  These structs use at least one type which differs in size between
  * 64-bit and 32-bit (e.g. pointers or long).  By convention, we require other
  * types to be of consistent size on 32-bit and 64-bit architectures.
  */
 
 #include "ppapi/tests/all_c_includes.h"
 
-#if !defined(__native_client__) && (defined(_M_X64) || defined(__x86_64__))
+#if !defined(__native_client__) && (defined(_M_X64) || defined(__x86_64__) || defined(__aarch64__))
 /* This section is for 64-bit compilation on Windows, Mac, and Linux.  Native
    client follows ILP32 even if -m64 is used, so NaCl code is explicitly treated
    as 32-bit.  This means pointers are always 4 bytes in native client, and it
    matches Win32  (see below).
  */
 #include "ppapi/tests/arch_dependent_sizes_64.h"
 #else
 /* This section is for compilation on 32-bit targets plus native client (in both
    32-bit and 64-bit mode, since native client always conforms to ILP32).
  */
 #include "ppapi/tests/arch_dependent_sizes_32.h"
 #endif