hurd: Fix some ld.so symbol override from libc

ld.so symbols to be overriden by libc need to be extern to really get
overriden.

	* sysdeps/mach/hurd/not-errno.h: New file.
	* sysdeps/mach/hurd/i386/localplt.data: Update accordingly.

ChangeLog

@@ -2,6 +2,7 @@
 
 	* sysdeps/mach/hurd/dl-unistd.h (__access, __brk, __lseek, __read,
 	__sbrk): Do not set attribute_hidden.
+	* sysdeps/mach/hurd/not-errno.h: New file.
 	* sysdeps/mach/hurd/i386/ld.abilist: Update accordingly.
 	* sysdeps/mach/hurd/i386/localplt.data: Update accordingly.
 

sysdeps/mach/hurd/i386/localplt.data

@@ -33,7 +33,7 @@ ld.so: __mmap
 ld.so: __fxstat64
 ld.so: __xstat64
 #ld.so: __access
-#ld.so: __access_noerrno
+ld.so: __access_noerrno
 ld.so: __getpid
 #ld.so: __getcwd
 ld.so: __sbrk

sysdeps/mach/hurd/not-errno.h

@@ -0,0 +1,21 @@
+/* Syscall wrapper that do not set errno.  Generic version.
+   Copyright (C) 2017-2018 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* The __access_noerrno stub mustn't be hidden in ld.so on Hurd since it needs
+   to be preempted by __access_noerrno from libc.so after bootstrap.  */
+extern __typeof (__access) __access_noerrno;