Remove thread refcount and remove NaClAppDtor()

src/native_client/src/trusted/service_runtime/nacl_syscall_common.c

 /*
  * Copyright 2008 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.
  */
 
 /*
  * NaCl service run-time, non-platform specific system call helper routines.
  */
 #include <sys/types.h>
@@ skipping 85 matching lines @@
   nacl_user[thread_idx] = NULL;
   nacl_thread[thread_idx] = NULL;
   NaClLog(3, " removing thread from thread table\n");
   NaClRemoveThreadMu(nap, natp->thread_num);
   NaClLog(3, " unlocking thread\n");
   NaClXMutexUnlock(&natp->mu);
   NaClLog(3, " announcing thread count change\n");
   NaClXCondVarBroadcast(&nap->threads_cv);
   NaClLog(3, " unlocking thread table\n");
   NaClXMutexUnlock(&nap->threads_mu);
-  NaClLog(3, " decref'ing thread object (from count %d)\n", natp->refcount);
-  NaClAppThreadDecRef(natp);
+  NaClLog(3, " freeing thread object\n");
+  NaClAppThreadDtor(natp);
   NaClLog(3, " NaClThreadExit\n");
   NaClThreadExit();  /* should not return */
   NaClLog(LOG_ERROR, "INCONCEIVABLE!\n");
   abort();
   /* NOTREACHED */
 }
 
 void NaClSysCommonThreadSyscallEnter(struct NaClAppThread *natp) {
   NaClLog(4, "NaClSysCommonThreadSyscallEnter: locking 0x%08"NACL_PRIxPTR"\n",
           (uintptr_t) &natp->mu);
@@ skipping 2591 matching lines @@
                                 void                  *code_target,
                                 void                  *code_buffer,
                                 size_t                code_size) {
   UNREFERENCED_PARAMETER(natp);
   UNREFERENCED_PARAMETER(code_target);
   UNREFERENCED_PARAMETER(code_buffer);
   UNREFERENCED_PARAMETER(code_size);
 
   return -NACL_ABI_ENOSYS;
 }