--- a/extern/libcompat/src/compat.h.in	Wed Feb 10 18:17:08 2021 +0100
+++ b/extern/libcompat/src/compat.h.in	Wed Feb 10 21:31:32 2021 +0100
@@ -1,3 +1,21 @@
+/*
+ * compat.h -- compatibility definitions
+ *
+ * Copyright (c) 2013-2021 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
 #ifndef LIBCOMPAT_COMPAT_H
 #define LIBCOMPAT_COMPAT_H
 
@@ -121,7 +139,6 @@
 extern int opterr;
 extern int optind;
 extern int optopt;
-extern int optreset;
 extern char *optarg;
 
 int