Fix for compiling. This change can be sent upstream

--- libproxy-master/libproxy/modules/config_gnome3.cpp Sat Sep 7 04:14:17 2013

+++ libproxy-master/libproxy/modules/config_gnome3.cpp Mon May 11 17:56:50 2015

@@ -25,6 +25,7 @@

#include <sys/stat.h> // For stat()

#include <unistd.h> // For pipe(), close(), vfork(), dup(), execl(), _exit()

#include <signal.h> // For kill()

+#include <string.h> // For memset()

#include "../extension_config.hpp"

using namespace libproxy;