message: [vcpkg] Fix build for non-windows
diff: @@ -79,7 +79,14 @@ namespace vcpkg::Commands::Env
  if (build_env_cmd.empty())
  return clean_env;
  else
  + {
  +#ifdef _WIN32
  return System::cmd_execute_modify_env(build_env_cmd, clean_env);
  +#else
  + Checks::exit_with_message(VCPKG_LINE_INFO,
  + "Build environment commands are not supported on this platform");
  +#endif
  + }
  }();
  std::string cmd = args.command_arguments.empty() ? "cmd" : args.command_arguments.at(0);
  