Include missing header to fix 64-bit issues.

Index: lib/getopt.c
--- lib/getopt.c.orig
+++ lib/getopt.c
@@ -29,6 +29,7 @@
 #include <config.h>
 #endif
 
+#include <string.h>
 #include <stdio.h>
 
 /* Comment out all this code if we are using the GNU C Library, and are not