wallet2: make use_fork_rules handle chain heights lower than leeway

src/wallet/wallet2.cpp

@@ -9688,7 +9688,7 @@ bool wallet2::use_fork_rules(uint8_t version, int64_t early_blocks) const
   result = m_node_rpc_proxy.get_earliest_height(version, earliest_height);
   throw_on_rpc_response_error(result, "get_hard_fork_info");
 
-  bool close_enough = height >= earliest_height - early_blocks && earliest_height != std::numeric_limits<uint64_t>::max(); // start using the rules that many blocks beforehand
+  bool close_enough = (int64_t)height >= (int64_t)earliest_height - early_blocks && earliest_height != std::numeric_limits<uint64_t>::max(); // start using the rules that many blocks beforehand
   if (close_enough)
     LOG_PRINT_L2("Using v" << (unsigned)version << " rules");
   else