gnulib: import sys_wait

A few sims use this to emulate process syscalls.
Gdb builds seem to still be fine.

gnulib/import/sys_wait.in.h

@@ -0,0 +1,131 @@
+/* A POSIX-like <sys/wait.h>.
+   Copyright (C) 2001-2003, 2005-2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
+
+
+#ifndef _@GUARD_PREFIX@_SYS_WAIT_H
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+@PRAGMA_COLUMNS@
+
+/* The include_next requires a split double-inclusion guard.  */
+#if !(defined _WIN32 && ! defined __CYGWIN__)
+# @INCLUDE_NEXT@ @NEXT_SYS_WAIT_H@
+#endif
+
+#ifndef _@GUARD_PREFIX@_SYS_WAIT_H
+#define _@GUARD_PREFIX@_SYS_WAIT_H
+
+/* Get pid_t.  */
+#include <sys/types.h>
+
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+
+#if !(defined _WIN32 && ! defined __CYGWIN__)
+/* Unix API.  */
+
+/* The following macros apply to an argument x, that is a status of a process,
+   as returned by waitpid().
+   On nearly all systems, including Linux/x86, WEXITSTATUS are bits 15..8 and
+   WTERMSIG are bits 7..0, while BeOS uses the opposite.  Therefore programs
+   have to use the abstract macros.  */
+
+/* For valid x, exactly one of WIFSIGNALED(x), WIFEXITED(x), WIFSTOPPED(x)
+   is true.  */
+# ifndef WIFSIGNALED
+#  define WIFSIGNALED(x) (WTERMSIG (x) != 0 && WTERMSIG(x) != 0x7f)
+# endif
+# ifndef WIFEXITED
+#  define WIFEXITED(x) (WTERMSIG (x) == 0)
+# endif
+# ifndef WIFSTOPPED
+#  define WIFSTOPPED(x) (WTERMSIG (x) == 0x7f)
+# endif
+
+/* The termination signal. Only to be accessed if WIFSIGNALED(x) is true.  */
+# ifndef WTERMSIG
+#  define WTERMSIG(x) ((x) & 0x7f)
+# endif
+
+/* The exit status. Only to be accessed if WIFEXITED(x) is true.  */
+# ifndef WEXITSTATUS
+#  define WEXITSTATUS(x) (((x) >> 8) & 0xff)
+# endif
+
+/* The stopping signal. Only to be accessed if WIFSTOPPED(x) is true.  */
+# ifndef WSTOPSIG
+#  define WSTOPSIG(x) (((x) >> 8) & 0x7f)
+# endif
+
+/* True if the process dumped core.  Not standardized by POSIX.  */
+# ifndef WCOREDUMP
+#  define WCOREDUMP(x) ((x) & 0x80)
+# endif
+
+#else
+/* Native Windows API.  */
+
+# include <signal.h> /* for SIGTERM */
+
+/* The following macros apply to an argument x, that is a status of a process,
+   as returned by waitpid() or, equivalently, _cwait() or GetExitCodeProcess().
+   This value is simply an 'int', not composed of bit fields.  */
+
+/* When an unhandled fatal signal terminates a process, the exit code is 3.  */
+# define WIFSIGNALED(x) ((x) == 3)
+# define WIFEXITED(x) ((x) != 3)
+# define WIFSTOPPED(x) 0
+
+/* The signal that terminated a process is not known posthum.  */
+# define WTERMSIG(x) SIGTERM
+
+# define WEXITSTATUS(x) (x)
+
+/* There are no stopping signals.  */
+# define WSTOPSIG(x) 0
+
+/* There are no core dumps.  */
+# define WCOREDUMP(x) 0
+
+#endif
+
+
+/* Declarations of functions.  */
+
+#if @GNULIB_WAITPID@
+# if defined _WIN32 && ! defined __CYGWIN__
+_GL_FUNCDECL_SYS (waitpid, pid_t, (pid_t pid, int *statusp, int options));
+# endif
+/* Need to cast, because on Cygwin, the second parameter is
+                                                __wait_status_ptr_t statusp.  */
+_GL_CXXALIAS_SYS_CAST (waitpid, pid_t, (pid_t pid, int *statusp, int options));
+_GL_CXXALIASWARN (waitpid);
+#elif defined GNULIB_POSIXCHECK
+# undef waitpid
+# if HAVE_RAW_DECL_WAITPID
+_GL_WARN_ON_USE (waitpid, "waitpid is unportable - "
+                 "use gnulib module sys_wait for portability");
+# endif
+#endif
+
+
+#endif /* _@GUARD_PREFIX@_SYS_WAIT_H */
+#endif /* _@GUARD_PREFIX@_SYS_WAIT_H */