make sure that libfwbuilder builds with gcc-4.3

--- libfwbuilder-2.1.17.orig/src/fwbuilder/IPAddress.h
+++ libfwbuilder-2.1.17/src/fwbuilder/IPAddress.h
@@ -29,6 +29,8 @@
 
 #include <string>
 #include <vector>
+#include <cstdlib>
+#include <cstring>
 
 #ifndef _WIN32
 #  include <sys/types.h>