throw when packet_buffer fails to allocate memory

src/packet_buffer.cpp

@@ -157,6 +157,9 @@ namespace libtorrent {
 			new_size <<= 1;
 
 		void** new_storage = (void**)malloc(sizeof(void*) * new_size);
+#ifndef BOOST_NO_EXCEPTIONS
+		if (new_storage == NULL) throw std::bad_alloc();
+#endif
 
 		for (index_type i = 0; i < new_size; ++i)
 			new_storage[i] = 0;