[hurd, commited] hurd: Move SINGLE_THREAD_P / RTLD_SINGLE_THREAD_P to single-thread.h

Like on Linux
---
 sysdeps/mach/hurd/single-thread.h | 26 ++++++++++++++++++++++++++
 sysdeps/mach/hurd/sysdep-cancel.h |  5 -----
 2 files changed, 26 insertions(+), 5 deletions(-)
 create mode 100644 sysdeps/mach/hurd/single-thread.h

diff --git a/sysdeps/mach/hurd/single-thread.h b/sysdeps/mach/hurd/single-thread.h
new file mode 100644
index 0000000000..7819978814
--- /dev/null
+++ b/sysdeps/mach/hurd/single-thread.h
@@ -0,0 +1,26 @@
+/* Single thread optimization, Hurd version.
+   Copyright (C) 2019-2026 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _SINGLE_THREAD_H
+#define _SINGLE_THREAD_H
+
+/* Always multi-thread (since there's at least the sig handler).  */
+#define SINGLE_THREAD_P (0)
+#define RTLD_SINGLE_THREAD_P (0)
+
+#endif /* _SINGLE_THREAD_H  */
diff --git a/sysdeps/mach/hurd/sysdep-cancel.h b/sysdeps/mach/hurd/sysdep-cancel.h
index 669c17151a..9311367ab9 100644
--- a/sysdeps/mach/hurd/sysdep-cancel.h
+++ b/sysdeps/mach/hurd/sysdep-cancel.h
@@ -6,11 +6,6 @@ void __pthread_disable_asynccancel (int oldtype);
 #pragma weak __pthread_enable_asynccancel
 #pragma weak __pthread_disable_asynccancel
 
-/* Always multi-thread (since there's at least the sig handler), but no
-   handling enabled.  */
-#define SINGLE_THREAD_P (0)
-#define RTLD_SINGLE_THREAD_P (0)
-
 #define LIBC_CANCEL_ASYNC() ({ \
 	int __cancel_oldtype = 0; \
 	if (__pthread_enable_asynccancel) \
-- 
2.53.0