[glibc] Fix build for hurd/thread-self.c for i386.

[glibc] Fix build for hurd/thread-self.c for i386.

[Samuel Thibault]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9cc27336c9b6fc7b59d1adbf36f0a044a0b89a59

commit 9cc27336c9b6fc7b59d1adbf36f0a044a0b89a59
Author: Flavio Cruz <flaviocruz@gmail.com>
Date:   Mon May 22 01:16:50 2023 -0400

    Fix build for hurd/thread-self.c for i386.
    
    We need to include hurd.h for libc_hidden_proto (__hurd_thread_self),
    introduced in b44c1e12524b ("hurd: Fix using interposable
    hurd_thread_self")
    
    This the error log:
    
    In file included from <command-line>:
    ./../include/libc-symbols.h:472:33: error: '__EI___hurd_thread_self' aliased to undefined symbol '__GI___hurd_thread_self'
      472 |   extern thread __typeof (name) __EI_##name \
          |                                 ^~~~~
    ./../include/libc-symbols.h:468:3: note: in expansion of macro '__hidden_ver2'
      468 |   __hidden_ver2 (, local, internal, name)
          |   ^~~~~~~~~~~~~
    ./../include/libc-symbols.h:476:41: note: in expansion of macro '__hidden_ver1'
      476 | #  define hidden_def(name)              __hidden_ver1(__GI_##name, name, name);
          |                                         ^~~~~~~~~~~~~
    ./../include/libc-symbols.h:557:32: note: in expansion of macro 'hidden_def'
      557 | # define libc_hidden_def(name) hidden_def (name)
          |                                ^~~~~~~~~~
    thread-self.c:27:1: note: in expansion of macro 'libc_hidden_def'
       27 | libc_hidden_def (__hurd_thread_self)
          | ^~~~~~~~~~~~~~~
    Message-Id: <ZGr6wj2UOxg3F0qH@jupiter.tail36e24.ts.net>

Diff:
---
 hurd/thread-self.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hurd/thread-self.c b/hurd/thread-self.c
index af013503bf..494a127aa5 100644
--- a/hurd/thread-self.c
+++ b/hurd/thread-self.c
@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <hurd.h>
 #include <hurd/signal.h>
 
 thread_t