gnulib: import various network functions

Some sim ports use these to provide networking functionality via the
dv-sockser module or via direct emulation for a few ports.

Gdb seems to build just fine still too.

gnulib/import/setsockopt.c

@@ -0,0 +1,65 @@
+/* setsockopt.c --- wrappers for Windows setsockopt function
+
+   Copyright (C) 2008-2021 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 of the License, 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/>.  */
+
+/* Written by Paolo Bonzini */
+
+#include <config.h>
+
+#define WIN32_LEAN_AND_MEAN
+/* Get winsock2.h. */
+#include <sys/socket.h>
+
+/* Get struct timeval. */
+#include <sys/time.h>
+
+/* Get set_winsock_errno, FD_TO_SOCKET etc. */
+#include "w32sock.h"
+
+#undef setsockopt
+
+int
+rpl_setsockopt (int fd, int level, int optname, const void *optval, socklen_t optlen)
+{
+  SOCKET sock = FD_TO_SOCKET (fd);
+  int r;
+
+  if (sock == INVALID_SOCKET)
+    {
+      errno = EBADF;
+      return -1;
+    }
+  else
+    {
+      if (level == SOL_SOCKET
+          && (optname == SO_RCVTIMEO || optname == SO_SNDTIMEO))
+        {
+          const struct timeval *tv = optval;
+          int milliseconds = tv->tv_sec * 1000 + tv->tv_usec / 1000;
+          optval = &milliseconds;
+          r = setsockopt (sock, level, optname, optval, sizeof (int));
+        }
+      else
+        {
+          r = setsockopt (sock, level, optname, optval, optlen);
+        }
+
+      if (r < 0)
+        set_winsock_errno ();
+
+      return r;
+    }
+}