aarch64/bits: provide sigstack.h

It fixes tst-signal6 and friends.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>

libc/sysdeps/linux/aarch64/bits/sigstack.h

@@ -0,0 +1,56 @@
+/* sigstack, sigaltstack definitions.
+   Copyright (C) 1998, 1999 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/>.  */
+
+#ifndef _SIGNAL_H
+# error "Never include this file directly.  Use <signal.h> instead"
+#endif
+
+
+#if defined __UCLIBC_SUSV4_LEGACY__ || !defined __UCLIBC_STRICT_HEADERS__
+/* Structure describing a signal stack (obsolete).  */
+struct sigstack
+  {
+    void *ss_sp;		/* Signal stack pointer.  */
+    int ss_onstack;		/* Nonzero if executing on this stack.  */
+  };
+#endif
+
+
+/* Possible values for `ss_flags.'.  */
+enum
+{
+  SS_ONSTACK = 1,
+#define SS_ONSTACK	SS_ONSTACK
+  SS_DISABLE
+#define SS_DISABLE	SS_DISABLE
+};
+
+/* Minimum stack size for a signal handler.  */
+#define MINSIGSTKSZ	5120
+
+/* System default stack size.  */
+#define SIGSTKSZ	16384
+
+
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;