Fix building on gcc 4.3

src/assert.cpp

@@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include <cxxabi.h>
 #include <string>
+#include <cstring>
 #include <stdlib.h>
 
 std::string demangle(char const* name)

src/lazy_bdecode.cpp

@@ -33,6 +33,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/lazy_entry.hpp"
 #include <iostream>
 #include <iomanip>
+#include <cstring>
 
 namespace libtorrent
 {