sequence of nested includes
<wchar.h> -> <stdio.h> -> <getopt.h> -> <stdlib.h>, and the latter includes
<stdint.h> and assumes its types are already defined. */
-#if ! (defined WCHAR_MIN && defined WCHAR_MAX)
+#if @HAVE_WCHAR_H@ && ! (defined WCHAR_MIN && defined WCHAR_MAX)
+ /* BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
+ included before <wchar.h>. */
+# include <stddef.h>
+# include <stdio.h>
+# include <time.h>
# define _GL_JUST_INCLUDE_SYSTEM_WCHAR_H
# include <wchar.h>
# undef _GL_JUST_INCLUDE_SYSTEM_WCHAR_H