Don't static compile on Darwin systems

Joel Grunbaum

2022-01-11 d14f48a147190989d9b58f7b56429ac8711be077

 protocol.hpp

@@ -12,6 +12,7 @@

// Catchup utilities
std::unordered_map<std::string, book::Book> recoverBook();
void catchUp(std::unordered_map<std::string, book::Book>& bs);

// Outgoing messages
json::Message* addOrder(json::AddMessage& order);