[MIPS] Make $t8 point to the address of TLS pointers

src/trusted/service_runtime/arch/mips/nacl_tls.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/include/nacl_platform.h"
 #include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/include/portability.h"
 #include "native_client/src/shared/platform/nacl_check.h"
@@ skipping 90 matching lines @@
    * Bias by 1: successful return value is never 0.
    */
   return idx + 1;
 }
 
 
 void NaClTlsFree(struct NaClAppThread *natp) {
   uint32_t idx = NaClGetThreadIdx(natp);
   NaClLog(2,
           "NaClTlsFree: old idx %d $tp %x\n",
-          idx, natp->user.t8);
+          idx, natp->user.tls_value1);
 
   NaClXMutexLock(&gNaClTlsMu);
   gNaClThreadIdxInUse[idx - 1] = 0;
   NaClXMutexUnlock(&gNaClTlsMu);
 
   natp->user.t8 = 0;
 }
 
 
 void NaClTlsSetTlsValue1(struct NaClAppThread *natp, uint32_t value) {
-  natp->user.t8 = value;
+  natp->user.tls_value1 = value;
 }
 
 
 void NaClTlsSetTlsValue2(struct NaClAppThread *natp, uint32_t value) {
   natp->user.tls_value2 = value;
 }
 
 
 uint32_t NaClTlsGetTlsValue1(struct NaClAppThread *natp) {
-  return natp->user.t8;
+  return natp->user.tls_value1;
 }
 
 
 uint32_t NaClTlsGetTlsValue2(struct NaClAppThread *natp) {
   return natp->user.tls_value2;
 }