config: Add missing HAVE_LIBUTIL_H define in config.h

Signed-off-by: Audrius Butkevicius <audrius.butkevicius@gmail.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

config.h.cmake

@@ -23,6 +23,9 @@
 /* Define to 1 if you have the <util.h> header file. */
 #cmakedefine HAVE_UTIL_H 1
 
+/* Define to 1 if you have the <libutil.h> header file. */
+#cmakedefine HAVE_LIBUTIL_H 1
+
 /* Define to 1 if you have the <termios.h> header file. */
 #cmakedefine HAVE_TERMIOS_H 1