hurd: Add stubs for missing libmes functions.

* lib/stub/lseek.c: New file.
* build-aux/configure-lib.sh (libmes_SOURCES)[gnu]: Add it.

build-aux/configure-lib.sh

@@ -103,6 +103,11 @@ lib/ctype/isxdigit.c
 lib/posix/write.c
 lib/stdlib/atoi.c
 "
+    if test $mes_kernel = gnu; then
+        libmes_SOURCES="$libmes_SOURCES
+lib/stub/lseek.c
+"
+    fi
     if test $mes_kernel = linux; then
         libmes_SOURCES="$libmes_SOURCES
 lib/linux/lseek.c

lib/stub/lseek.c

@@ -0,0 +1,35 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes 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.
+ *
+ * GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <mes/lib.h>
+#include <errno.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+off_t
+lseek (int filedes, off_t offset, int whence)
+{
+  static int stub = 0;
+  if (__mes_debug () && !stub)
+    eputs ("lseek stub\n");
+  stub = 1;
+  errno = 0;
+  return 0;
+}