Replace #define syscalls cancel machinery.

nptl/sysdeps/x86_64/tls.h

 /* Definition for thread-local data handling.  nptl/x86_64 version.
    Copyright (C) 2002,2003,2004,2005,2006,2007 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
 
    The GNU C Library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with the GNU C Library; if not, write to the Free
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
 #ifndef _TLS_H
 #define _TLS_H  1
 
 #ifndef __ASSEMBLER__
 # include <asm/prctl.h> /* For ARCH_SET_FS.  */
 # include <stdbool.h>
 # include <stddef.h>
 # include <stdint.h>
 # include <stdlib.h>
+/* Return the thread descriptor for the current thread.
+
+   The contained asm must *not* be marked volatile since otherwise
+   assignments like
+        pthread_descr self = thread_self();
+   do not get optimized away.
+
+   We need it before sysdep.h in NaCl for INTERNAL_SYSCALL_gettid_0.  */
+#ifdef __native_client__
+void* __nacl_read_tp (void) __attribute__ ((const));
+# define THREAD_SELF ((struct pthread *)__nacl_read_tp ())
+#endif
 # include <sysdep.h>
 # include <kernel-features.h>
 
 
 /* Type for the dtv.  */
 typedef union dtv
 {
   size_t counter;
   struct
   {
@@ skipping 140 matching lines @@
      THREAD_GETMEM (__pd, header.dtv); })
 #endif
 
 
 /* Return the thread descriptor for the current thread.
 
    The contained asm must *not* be marked volatile since otherwise
    assignments like
         pthread_descr self = thread_self();
    do not get optimized away.  */
-#ifdef __native_client__
-void* __nacl_read_tp (void) __attribute__ ((const));
-# define THREAD_SELF ((struct pthread *)__nacl_read_tp ())
-#else
+#ifndef __native_client__
 # define THREAD_SELF \
   ({ struct pthread *__self;                                                  \
      asm ("movq %%fs:%c1,%q0" : "=r" (__self)                                 \
           : "i" (offsetof (struct pthread, header.self)));                    \
      __self;})
 #endif
 
 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 # define DB_THREAD_SELF_INCLUDE  <sys/reg.h> /* For the FS constant.  */
 # define DB_THREAD_SELF CONST_THREAD_AREA (64, FS)
@@ skipping 214 matching lines @@
   while (0)
 #endif
 #define THREAD_GSCOPE_SET_FLAG() \
   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 #define THREAD_GSCOPE_WAIT() \
   GL(dl_wait_lookup_done) ()
 
 #endif /* __ASSEMBLER__ */
 
 #endif  /* tls.h */