Enable syscall_test on windows.

src/shared/platform/win/nacl_host_desc.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.
  */
 
 /*
  * NaCl Service Runtime.  I/O Descriptor / Handle abstraction.  Memory
  * mapping using descriptors.
  */
@@ skipping 1321 matching lines @@
   }
 
   return 0;
 }
 
 int NaClHostDescIsatty(struct NaClHostDesc *d) {
   int retval;
 
   NaClHostDescCheckValidity("NaClHostDescIsatty", d);
   retval = _isatty(d->d);
-  /* When _isatty fails it returns zero and sets errno. */
-  return (0 == retval) ? -NaClXlateErrno(errno) : 1;
+  /* When windows _isatty fails it returns zero, but does not set errno. */
+  return (0 == retval) ? -NACL_ABI_ENOTTY : 1;
 }
 
 int NaClHostDescClose(struct NaClHostDesc *d) {
   int retval;
 
   NaClHostDescCheckValidity("NaClHostDescClose", d);
   if (-1 != d->d) {
     retval = _close(d->d);
     if (-1 == retval) {
       return -GetErrno();
@@ skipping 40 matching lines @@
   if (_getcwd(path, (int) len) == NULL)
     return -NaClXlateErrno(errno);
   return 0;
 }
 
 int NaClHostDescUnlink(const char *path) {
   if (_unlink(path) != 0)
     return -errno;
   return 0;
 }