Allow end user to configure what ports to listen on

sunshine/main.cpp

@@ -270,4 +270,8 @@ int write_file(const char *path, const std::string_view &contents) {
   out << contents;
 
   return 0;
+}
+
+std::uint16_t map_port(int port) {
+  return (std::uint16_t)((int)config::sunshine.port + port);
 }