Add __safe_fatal and use it in __pthread_unwind forwarder fallback.

sysdeps/unix/sysv/linux/safe-fatal.h

@@ -0,0 +1,33 @@
+/* Crash the process immediately, without possibility of deadlock.  Linux.
+   Copyright (C) 2014 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 _SAFE_FATAL_H
+#define _SAFE_FATAL_H   1
+
+#include <sysdep.h>
+#include <unistd.h>
+
+static inline void
+__safe_fatal (void)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  pid_t self = INTERNAL_SYSCALL (getpid, err, 0);
+  INTERNAL_SYSCALL (kill, err, 2, self, SIGKILL);
+}
+
+#endif  /* safe-fatal.h */